diff --git a/.vscode/c_cpp_properties.json b/.vscode/c_cpp_properties.json
index e69de29bb..a25a72751 100644
--- a/.vscode/c_cpp_properties.json
+++ b/.vscode/c_cpp_properties.json
@@ -0,0 +1,25 @@
+{
+    "configurations": [
+        {
+            "name": "Linux",
+            "includePath": [
+                "${workspaceFolder}/**",
+                "/usr/lib/x86_64-linux-gnu/openmpi/include",
+                "/usr/local/include/vtk-9.2/**",
+                "/home/lmottet/Work/Software/ParMmg/**",
+                "/home/lmottet/Work/Software/mmg/**",
+                "/home/lmottet/Work/Software/mmg/build-dev/include/**",
+                "/home/lmottet/Work/Software/mmg/build-dev/lib/**",
+                "/home/lmottet/Work/Software/mmg/build-*/include/**",
+                "/home/lmottet/Work/Software/mmg/build-*/lib/**"
+
+            ],
+            "defines": [],
+            "compilerPath": "/usr/bin/mpirun",
+            "cStandard": "gnu17",
+            "cppStandard": "gnu++14",
+            "intelliSenseMode": "linux-gcc-x64"
+        }
+    ],
+    "version": 4
+}
diff --git a/cmake/testing/code/mmg_get_tagname.c b/cmake/testing/code/mmg_get_tagname.c
new file mode 100644
index 000000000..e8af8f669
--- /dev/null
+++ b/cmake/testing/code/mmg_get_tagname.c
@@ -0,0 +1,23 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "libmmgcommon_private.h"
+
+int main() {
+
+  uint16_t tag;
+  char *tags_name;
+
+  tag = 0;
+  printf("%s\n", MMG5_Get_tagName(tag));
+
+  tag = UINT16_MAX;
+  printf("%s\n", MMG5_Get_tagName(tag));
+
+  tag &= ~MG_NUL;
+  printf("%s\n", MMG5_Get_tagName(tag));
+
+
+  return 0;
+
+}
diff --git a/cmake/testing/code/ridge-preservation-in-ls-mode.c b/cmake/testing/code/ridge-preservation-in-ls-mode.c
index f8b65d755..11e9c3a42 100644
--- a/cmake/testing/code/ridge-preservation-in-ls-mode.c
+++ b/cmake/testing/code/ridge-preservation-in-ls-mode.c
@@ -131,7 +131,7 @@ int main(int argc,char *argv[]) {
     MMG5_pEdge ped = &mesh1->edge[k];
     if ( ped->tag & MG_GEO ) {
       MMG5_int ref;
-      int16_t  tag;
+      uint16_t tag;
       if ( !MMG5_hGet(&hash,ped->a,ped->b,&ref,&tag) ) {
         continue;
       }
diff --git a/cmake/testing/mmg_tests.cmake b/cmake/testing/mmg_tests.cmake
index 34427728a..6f1c8883a 100644
--- a/cmake/testing/mmg_tests.cmake
+++ b/cmake/testing/mmg_tests.cmake
@@ -424,6 +424,65 @@ ADD_TEST(NAME mmg_CommandLineAni_${SHRT_EXEC}
     ${MMG_CI_TESTS}/SurfEdges_house/housebad.meshb
     -out ${CTEST_OUTPUT_DIR}/mmg_SurfEdges_OptimAni_${SHRT_EXEC}.o.meshb)
 
+ENDFOREACH()
 
+# Unit tests
+## Really not clean: as the organization of the functions definition in .c files
+## and headers declatation in .h files is very badly done (and has never been
+## cleaned), and we try to test a private function of Mmg, we have to include
+## almost all the .c/.h files to be able to build this unit test.
+##
+## Not built and tested on windows due to unallowed definition of dllimport data
+##
 
-ENDFOREACH()
+IF ( NOT WIN32 )
+  FILE(
+    GLOB
+    mmg_get_tagname_files
+    ${mmg2d_library_files}
+    ${mmg3d_library_files}
+    ${mmgs_library_files}
+    ${PROJECT_SOURCE_DIR}/cmake/testing/code/mmg_get_tagname.c
+  )
+
+  ADD_EXECUTABLE (  mmg_get_tagname  ${mmg_get_tagname_files} )
+
+  ADD_DEPENDENCIES ( mmg_get_tagname copy_mmgcommon_headers
+    copy_3d_headers copy_2d_headers copy_s_headers )
+
+
+  IF ( CMAKE_VERSION VERSION_LESS 2.8.12 )
+    INCLUDE_DIRECTORIES ( BEFORE
+      ${MMGCOMMON_SOURCE_DIR} ${PROJECT_BINARY_DIR}/include
+      ${PROJECT_BINARY_DIR}/src/common )
+    if ( SCOTCH_FOUND AND NOT USE_SCOTCH MATCHES OFF )
+      INCLUDE_DIRECTORIES ( AFTER ${SCOTCH_INCLUDE_DIRS} )
+    ENDIF()
+
+    IF( ELAS_FOUND AND NOT USE_ELAS MATCHES OFF )
+      # Set flags for building test program
+      INCLUDE_DIRECTORIES(AFTER ${ELAS_INCLUDE_DIR})
+      SET( GET_TAGNAME_LIBRARIES ${ELAS_LINK_FLAGS} ${ELAS_LIBRARY} ${LIBRARIES})
+
+    ENDIF ( )
+
+
+  ELSE ( )
+    TARGET_INCLUDE_DIRECTORIES ( mmg_get_tagname BEFORE PUBLIC
+      ${MMGCOMMON_SOURCE_DIR} ${PROJECT_BINARY_DIR}/include
+      ${PROJECT_BINARY_DIR}/src/common
+    )
+    if ( SCOTCH_FOUND AND NOT USE_SCOTCH MATCHES OFF )
+      target_include_directories( mmg_get_tagname BEFORE PUBLIC ${SCOTCH_INCLUDE_DIRS} )
+    ENDIF ( )
+
+    IF( ELAS_FOUND AND NOT USE_ELAS MATCHES OFF )
+      target_include_directories( mmg_get_tagname AFTER PUBLIC ${ELAS_INCLUDE_DIR} )
+      SET( GET_TAGNAME_LIBRARIES ${ELAS_LINK_FLAGS} ${ELAS_LIBRARY} ${LIBRARIES})
+    ENDIF ( )
+
+  ENDIF ( )
+
+  TARGET_LINK_LIBRARIES ( mmg_get_tagname PRIVATE ${GET_TAGNAME_LIBRARIES}  )
+
+ENDIF ( )
diff --git a/src/common/API_functions.c b/src/common/API_functions.c
index 06c759fab..706c0471e 100644
--- a/src/common/API_functions.c
+++ b/src/common/API_functions.c
@@ -734,7 +734,7 @@ const char* MMG5_Get_typeName(enum MMG5_type typ)
   }
 }
 
-const char* MMG5_Get_tagName(int tag)
+const char* MMG5_Get_tagName(uint16_t tag)
 {
   static char tags_name[1024];
 
@@ -791,7 +791,12 @@ const char* MMG5_Get_tagName(int tag)
 
   if ( tag & MG_PARBDY) {
     strcat(tags_name,"Parbdy ");
-    }
+  }
+
+  if ( tag & MG_OVERLAP) {
+    strcat(tags_name,"Overlap ");
+  }
+
   strcat(tags_name,"tag(s).");
 
   return tags_name;
diff --git a/src/common/hash.c b/src/common/hash.c
index 811e2b85e..ce1f5d11b 100644
--- a/src/common/hash.c
+++ b/src/common/hash.c
@@ -438,7 +438,7 @@ int MMG5_hashUpdate(MMG5_Hash *hash, MMG5_int a,MMG5_int b,MMG5_int k) {
  * tag. If the edge exist, add the new tag to the already stored tags.
  *
  */
-int MMG5_hashEdgeTag(MMG5_pMesh mesh,MMG5_Hash *hash, MMG5_int a,MMG5_int b,int16_t tag) {
+int MMG5_hashEdgeTag(MMG5_pMesh mesh,MMG5_Hash *hash, MMG5_int a,MMG5_int b,uint16_t tag) {
   MMG5_hedge  *ph;
   MMG5_int     key;
   MMG5_int    ia,ib,j;
diff --git a/src/common/libmmgcommon_private.h b/src/common/libmmgcommon_private.h
index ba3d0bf7a..6687d2894 100644
--- a/src/common/libmmgcommon_private.h
+++ b/src/common/libmmgcommon_private.h
@@ -300,7 +300,7 @@ LIBMMG_CORE_EXPORT int MMG5_Compute_constantSize(MMG5_pMesh mesh,MMG5_pSol met,d
  *
  * \warning for debug purpose, no thread safe.
  */
-const char* MMG5_Get_tagName(int tag);
+const char* MMG5_Get_tagName(uint16_t tag);
 
 /**
  * \param mesh pointer to the mesh structure.
diff --git a/src/common/libmmgtypes.h b/src/common/libmmgtypes.h
index 2c373593d..fe75d6193 100644
--- a/src/common/libmmgtypes.h
+++ b/src/common/libmmgtypes.h
@@ -287,7 +287,7 @@ typedef struct {
                   the unused points)*/
   MMG5_int flag; /*!< Flag to know if we have already treated the point */
   MMG5_int s;
-  int16_t  tag; /*!< Contains binary flags : if \f$tag=23=16+4+2+1\f$, then
+  uint16_t  tag; /*!< Contains binary flags : if \f$tag=23=16+4+2+1\f$, then
                   the point is \a MG_REF, \a MG_GEO, \a MG_REQ and \a MG_BDY */
   int8_t   tagdel; /*!< Tag for delaunay */
 } MMG5_Point;
@@ -313,7 +313,7 @@ typedef struct {
   MMG5_int ref; /*!< Reference of the edge */
   MMG5_int base; /*!< 2Donly: used to store the tria+ tria edge indices
                    that allow to access to the edge */
-  int16_t  tag; /*!< Binary flags */
+  uint16_t  tag; /*!< Binary flags */
 } MMG5_Edge;
 typedef MMG5_Edge * MMG5_pEdge;
 
@@ -345,7 +345,7 @@ typedef struct {
   MMG5_int edg[3]; /*!< edg[i] contains the ref of the \f$i^{th}\f$ edge
                      of triangle */
   MMG5_int flag;
-  int16_t  tag[3]; /*!< tag[i] contains the tag associated to the
+  uint16_t  tag[3]; /*!< tag[i] contains the tag associated to the
                      \f$i^{th}\f$ edge of triangle */
   } MMG5_Tria;
 typedef MMG5_Tria * MMG5_pTria;
@@ -375,7 +375,7 @@ typedef struct {
   MMG5_int base;
   MMG5_int edg[4]; /*!< edg[i] contains the ref of the \f$i^{th}\f$ edge
                      of quadrangle */
-  int16_t  tag[4]; /*!< tag[i] contains the tag associated to the
+  uint16_t  tag[4]; /*!< tag[i] contains the tag associated to the
                      \f$i^{th}\f$ edge of quadrangle */
 } MMG5_Quad;
 typedef MMG5_Quad * MMG5_pQuad;
@@ -414,7 +414,7 @@ typedef struct {
                  tetrahedron (only for tetrahedra that are adjacent to
                  surfaces) */
   MMG5_int flag;
-  int16_t  tag;
+  uint16_t  tag;
 } MMG5_Tetra;
 typedef MMG5_Tetra * MMG5_pTetra;
 
@@ -427,9 +427,9 @@ typedef struct {
                      \f$i^{th}\f$ vertex of the tetrahedron;*/
   MMG5_int edg[6]; /*!< edg[i] contains the reference of the
                      \f$i^{th}\f$ edge of the tetrahedron */
-  int16_t  ftag[4]; /*!< ftag[i] contains the tag associated to the
+  uint16_t  ftag[4]; /*!< ftag[i] contains the tag associated to the
                       \f$i^{th}\f$ face of the tetrahedron */
-  int16_t  tag[6]; /*!< tag[i] contains the tag associated to the
+  uint16_t  tag[6]; /*!< tag[i] contains the tag associated to the
                      \f$i^{th}\f$ edge of the tetrahedron */
   int8_t   ori; /*!< Orientation of the triangles of the tetrahedron:
                   the $\f$i^{th}\f$ bit of ori is set to 0 when the
@@ -473,7 +473,7 @@ typedef struct {
   MMG5_int flag;
   MMG5_int xpr; /*!< Index of the surface \ref MMG5_xPrism associated to
                   the prism*/
-  int8_t   tag;
+  uint8_t   tag;
 } MMG5_Prism;
 typedef MMG5_Prism * MMG5_pPrism;
 
@@ -488,9 +488,9 @@ typedef struct {
                     * edg[0]={0,1},edg[1]={0,2},edg[2]={0,3},edg[3]={1,2},
                     * edg[4]={1,4},edg[5]={2,5},edg[6]={3,4},edg[7]={3,5},
                     * edg[8]={4,5}*/
-  int16_t  ftag[5]; /*!< ftag[i] contains the tag associated to the
+  uint16_t  ftag[5]; /*!< ftag[i] contains the tag associated to the
                       \f$i^{th}\f$ face of the prism */
-  int16_t  tag[9]; /*!< tag[i] contains the tag associated to the
+  uint16_t  tag[9]; /*!< tag[i] contains the tag associated to the
                      \f$i^{th}\f$ edge of the prism */
 } MMG5_xPrism;
 typedef MMG5_xPrism * MMG5_pxPrism;
@@ -572,7 +572,7 @@ typedef struct {
   MMG5_int     b;  /*!< Second extremity of edge */
   MMG5_int     ref; /*!< Reference or idx (2D) of edge */
   MMG5_int     nxt; /*!< Next element of hash table */
-  int16_t      tag; /*!< tag of edge */
+  uint16_t     tag; /*!< tag of edge */
 } MMG5_hgeom;
 
 /**
diff --git a/src/common/mmgcommon_private.h b/src/common/mmgcommon_private.h
index 1e139dbac..36b44291b 100644
--- a/src/common/mmgcommon_private.h
+++ b/src/common/mmgcommon_private.h
@@ -153,7 +153,8 @@ extern "C" {
 #define  MG_OLDPARBDY (1 << 11)       /**< 2048 old parallel boundary */
 #define  MG_PARBDYBDY (1 << 12)       /**< 4096 parallel boundary over a boundary */
 #define  MG_PARBDY    (1 << 13)       /**< 8192 parallel boundary */
-#define  MG_NUL       (1 << 14)       /**< 16384 vertex removed */
+#define  MG_OVERLAP   (1 << 14)       /**< 16384 elements on overlap */
+#define  MG_NUL       (1 << 15)       /**< 32768 vertex removed */
 
 /* binary tags for local parameters */
 #define  MG_Vert   (1 << 0 )  /**< 1 local parameter applied over vertex */
@@ -676,7 +677,7 @@ typedef struct MMG5_iNode_s {
  MMG5_int      MMG5_hashFace(MMG5_pMesh,MMG5_Hash*,MMG5_int,MMG5_int,MMG5_int,MMG5_int);
  int           MMG5_hashEdge(MMG5_pMesh mesh,MMG5_Hash *hash,MMG5_int a,MMG5_int b,MMG5_int k);
  int           MMG5_hashUpdate(MMG5_Hash *hash,MMG5_int a,MMG5_int b,MMG5_int k);
- int           MMG5_hashEdgeTag(MMG5_pMesh mesh,MMG5_Hash *hash,MMG5_int a,MMG5_int b,int16_t k);
+ int           MMG5_hashEdgeTag(MMG5_pMesh mesh,MMG5_Hash *hash,MMG5_int a,MMG5_int b,uint16_t k);
  MMG5_int      MMG5_hashGet(MMG5_Hash *hash,MMG5_int a,MMG5_int b);
  int           MMG5_hashNew(MMG5_pMesh mesh, MMG5_Hash *hash,MMG5_int hsiz,MMG5_int hmax);
  int           MMG5_intmetsavedir(MMG5_pMesh mesh, double *m,double *n,double *mr);
diff --git a/src/mmg2d/analys_2d.c b/src/mmg2d/analys_2d.c
index 7da68a639..ded88b655 100644
--- a/src/mmg2d/analys_2d.c
+++ b/src/mmg2d/analys_2d.c
@@ -51,7 +51,7 @@ int MMG2D_setadj(MMG5_pMesh mesh, int8_t init_cc) {
   MMG5_pTria       pt,pt1;
   MMG5_pQuad       pq;
   MMG5_int         *pile,*adja,ipil,k,kk,ncc,ip1,ip2,nr,nref;
-  int16_t          tag;
+  uint16_t         tag;
   int8_t           i,ii,i1,i2;
 
   if ( !mesh->nt ) {
diff --git a/src/mmg2d/libmmg2d_private.h b/src/mmg2d/libmmg2d_private.h
index c301f5855..a700cf5f5 100644
--- a/src/mmg2d/libmmg2d_private.h
+++ b/src/mmg2d/libmmg2d_private.h
@@ -185,7 +185,7 @@ static const unsigned int MMG2D_idir[5] = {0,1,2,0,1};
 
 /* Prototypes */
 /*zaldy*/
-MMG5_int MMG2D_newPt(MMG5_pMesh mesh,double c[2],int16_t tag);
+MMG5_int MMG2D_newPt(MMG5_pMesh mesh,double c[2],uint16_t tag);
 void MMG2D_delPt(MMG5_pMesh mesh,MMG5_int ip) ;
 void MMG5_delEdge(MMG5_pMesh mesh,MMG5_int iel);
 MMG5_int MMG2D_newElt(MMG5_pMesh mesh);
diff --git a/src/mmg2d/zaldy_2d.c b/src/mmg2d/zaldy_2d.c
index 3489dbc0a..865180e2d 100644
--- a/src/mmg2d/zaldy_2d.c
+++ b/src/mmg2d/zaldy_2d.c
@@ -35,7 +35,7 @@
 
 
 /* Create a new vertex in the mesh, and return its number */
-MMG5_int MMG2D_newPt(MMG5_pMesh mesh,double c[2],int16_t tag) {
+MMG5_int MMG2D_newPt(MMG5_pMesh mesh,double c[2],uint16_t tag) {
   MMG5_pPoint  ppt;
   MMG5_int     curpt;
 
diff --git a/src/mmg3d/analys_3d.c b/src/mmg3d/analys_3d.c
index f0a2d5ce7..9c076e19d 100644
--- a/src/mmg3d/analys_3d.c
+++ b/src/mmg3d/analys_3d.c
@@ -109,7 +109,7 @@ int MMG5_setadj(MMG5_pMesh mesh){
   MMG5_pTria   pt,pt1;
   MMG5_int     *adja,*adjb,adji1,adji2,*pile,iad,ipil,ip1,ip2,gen;
   MMG5_int     k,kk,iel,jel,nvf,nf,nr,nm,nt,nre,nreq,ncc,ned,ref;
-  int16_t      tag;
+  uint16_t     tag;
   int8_t       i,ii,i1,i2,ii1,ii2,voy;
 
   nvf = nf = ncc = ned = 0;
diff --git a/src/mmg3d/anisomovpt_3d.c b/src/mmg3d/anisomovpt_3d.c
index d88a4b100..ceabaa2fa 100644
--- a/src/mmg3d/anisomovpt_3d.c
+++ b/src/mmg3d/anisomovpt_3d.c
@@ -503,7 +503,7 @@ int MMG5_movbdyregpt_ani(MMG5_pMesh mesh, MMG5_pSol met, MMG3D_pPROctree PROctre
  */
 static inline
 int MMG3D_movbdycurvept_ani(MMG5_pMesh mesh, MMG5_pSol met, MMG3D_pPROctree PROctree,int64_t *listv,
-                            int ilistv,MMG5_int *lists, int ilists,int improve,const int16_t edgTag){
+                            int ilistv,MMG5_int *lists, int ilists,int improve,const uint16_t edgTag){
   MMG5_pTetra           pt;
   MMG5_pPoint           p0;
   MMG5_Tria             tt;
diff --git a/src/mmg3d/boulep_3d.c b/src/mmg3d/boulep_3d.c
index a2b37f5a5..e02308f9d 100644
--- a/src/mmg3d/boulep_3d.c
+++ b/src/mmg3d/boulep_3d.c
@@ -202,7 +202,7 @@ int MMG5_boulenm(MMG5_pMesh mesh,MMG5_int start,int ip,int iface,
   double        dd,nt[3];
   int           nr,nnm;
   MMG5_int      base,nump,k,*adja,piv,nvstart,aux,na,nb,adj,fstart,ip0,ip1;
-  int16_t       tag;
+  uint16_t      tag;
   int8_t        iopp,ipiv,indb,inda,i,isface;
   int8_t        indedg[4][4] = { {-1,0,1,2}, {0,-1,3,4}, {1,3,-1,5}, {2,4,5,-1} };
 
@@ -1176,11 +1176,11 @@ int MMG5_bouletrid(MMG5_pMesh mesh,MMG5_int start,int iface,int ip,int *il1,MMG5
  */
 static inline
 int MMG3D_settag_oneDir(MMG5_pMesh  mesh,MMG5_int start, MMG5_int na, MMG5_int nb,
-                                     int16_t tag,int edg, MMG5_int piv,MMG5_int adj) {
+                                     uint16_t tag,int edg, MMG5_int piv,MMG5_int adj) {
   MMG5_pTetra  pt;
   MMG5_pxTetra pxt;
   MMG5_int     *adja;
-  int16_t      taginit;
+  uint16_t     taginit;
   int8_t       i;
 
   while ( adj && (adj != start) ) {
@@ -1231,11 +1231,11 @@ int MMG3D_settag_oneDir(MMG5_pMesh  mesh,MMG5_int start, MMG5_int na, MMG5_int n
  * travelling its shell.
  *
  */
-int MMG5_settag(MMG5_pMesh mesh,MMG5_int start,int ia,int16_t tag,int edg) {
+int MMG5_settag(MMG5_pMesh mesh,MMG5_int start,int ia,uint16_t tag,int edg) {
   MMG5_pTetra        pt;
   MMG5_pxTetra       pxt;
   MMG5_int           na,nb,*adja,adj,piv;
-  int16_t            taginit;
+  uint16_t           taginit;
 
   assert( start >= 1 );
   pt = &mesh->tetra[start];
@@ -1298,7 +1298,7 @@ int MMG5_settag(MMG5_pMesh mesh,MMG5_int start,int ia,int16_t tag,int edg) {
  */
 static inline
 int MMG3D_deltag_oneDir(MMG5_pMesh  mesh,MMG5_int start, MMG5_int na, MMG5_int nb,
-                        int16_t tag,MMG5_int piv,MMG5_int adj) {
+                        uint16_t tag,MMG5_int piv,MMG5_int adj) {
   MMG5_pTetra  pt;
   MMG5_pxTetra pxt;
   MMG5_int     *adja;
@@ -1344,7 +1344,7 @@ int MMG3D_deltag_oneDir(MMG5_pMesh  mesh,MMG5_int start, MMG5_int na, MMG5_int n
  * shell.
  *
  */
-int MMG5_deltag(MMG5_pMesh mesh,MMG5_int start,int ia,int16_t tag) {
+int MMG5_deltag(MMG5_pMesh mesh,MMG5_int start,int ia,uint16_t tag) {
   MMG5_pTetra        pt;
   MMG5_pxTetra       pxt;
   MMG5_int           na,nb,*adja,adj,piv;
diff --git a/src/mmg3d/chkmsh_3d.c b/src/mmg3d/chkmsh_3d.c
index 845cd6310..031883f38 100644
--- a/src/mmg3d/chkmsh_3d.c
+++ b/src/mmg3d/chkmsh_3d.c
@@ -90,7 +90,7 @@ void MMG5_chkvol(MMG5_pMesh mesh) {
  */
 static inline
 int MMG3D_chk_shellEdgeTag_oneDir(MMG5_pMesh  mesh,MMG5_int start, MMG5_int na, MMG5_int nb,
-                                  int16_t tag,MMG5_int ref, MMG5_int piv,MMG5_int adj) {
+                                  uint16_t tag,MMG5_int ref, MMG5_int piv,MMG5_int adj) {
   MMG5_pTetra  pt;
   MMG5_pxTetra pxt;
   MMG5_int     *adja;
@@ -139,7 +139,7 @@ int MMG3D_chk_shellEdgeTag_oneDir(MMG5_pMesh  mesh,MMG5_int start, MMG5_int na,
  * traveling its shell.
  *
  */
-int MMG3D_chk_shellEdgeTag(MMG5_pMesh  mesh,MMG5_int start, int8_t ia,int16_t tag,MMG5_int ref) {
+int MMG3D_chk_shellEdgeTag(MMG5_pMesh  mesh,MMG5_int start, int8_t ia,uint16_t tag,MMG5_int ref) {
   MMG5_pTetra  pt;
   MMG5_pxTetra pxt;
   MMG5_int     piv,na,nb,adj,*adja;
@@ -235,7 +235,7 @@ void MMG3D_chkmeshedgestags(MMG5_pMesh mesh) {
         ip1 = pt->v[MMG5_iare[i][0]];
         ip2 = pt->v[MMG5_iare[i][1]];
 
-        int16_t tag = 0;
+        uint16_t tag = 0;
         MMG5_int dummy = 0;
         int ier = MMG5_hGet ( &hash,ip1,ip2,&dummy,&tag);
 
@@ -899,7 +899,7 @@ int srcface(MMG5_pMesh mesh,MMG5_int n0,MMG5_int n1,MMG5_int n2) {
   MMG5_pTetra   pt;
   MMG5_pxTetra  pxt;
   MMG5_int      ref,minn,maxn,sn,k,ip0,ip1,ip2,mins,maxs,sum;
-  int16_t       tag;
+  uint16_t      tag;
   int8_t        i;
   static int8_t mmgWarn0 = 0;
 
diff --git a/src/mmg3d/colver_3d.c b/src/mmg3d/colver_3d.c
index f31f46606..30aed7edd 100644
--- a/src/mmg3d/colver_3d.c
+++ b/src/mmg3d/colver_3d.c
@@ -379,7 +379,7 @@ MMG5_topchkcol_bdy(MMG5_pMesh mesh,MMG5_int k,int iface,int8_t iedg,MMG5_int *li
  */
 static inline
 int MMG3D_get_shellEdgeTag_oneDir(MMG5_pMesh  mesh,MMG5_int start, MMG5_int na, MMG5_int nb,
-                                  int16_t *tag,MMG5_int *ref, MMG5_int piv,MMG5_int adj,
+                                  uint16_t *tag,MMG5_int *ref, MMG5_int piv,MMG5_int adj,
                                   int8_t *filled) {
   MMG5_pTetra  pt;
   MMG5_pxTetra pxt;
@@ -436,7 +436,7 @@ int MMG3D_get_shellEdgeTag_oneDir(MMG5_pMesh  mesh,MMG5_int start, MMG5_int na,
  * consistent through the edge shell);
  *
  */
-int MMG3D_get_shellEdgeTag(MMG5_pMesh  mesh,MMG5_int start, int8_t ia,int16_t *tag,MMG5_int *ref) {
+int MMG3D_get_shellEdgeTag(MMG5_pMesh  mesh,MMG5_int start, int8_t ia,uint16_t *tag,MMG5_int *ref) {
   MMG5_pTetra  pt;
   MMG5_pxTetra pxt;
   MMG5_int     piv,na,nb,adj,*adja;
@@ -535,7 +535,7 @@ int MMG5_chkcol_bdy(MMG5_pMesh mesh,MMG5_pSol met,MMG5_int k,int8_t iface,
   double       ps,devold,devnew,hmax,hausd;
   MMG5_int     nump,numq,ndepmin,ndepplus,l,kk,iel;
   int          nr,nbbdy,isloc,iedgeOpp,ipp;
-  int16_t      tag;
+  uint16_t     tag;
   int8_t       iopp,iopp2,ia,ip,i,iq,i0,i1,ier,isminp,isplp;
 #ifndef NDEBUG
   MMG5_pPoint  p0;
@@ -635,7 +635,7 @@ int MMG5_chkcol_bdy(MMG5_pMesh mesh,MMG5_pSol met,MMG5_int k,int8_t iface,
          *  shell because some MG_BDY tags may be missings due to the creation
          *  of an xtetra during a previous collapse */
         if ( (!pt->xt) || !(pxt->ftag[i] & MG_BDY) ) {
-          int16_t  tag0,tag1,tag2;
+          uint16_t  tag0,tag1,tag2;
           MMG5_int ref0,ref1,ref2;
 
           tag0 = tag1 = tag2 = 0;
@@ -954,7 +954,7 @@ void MMG3D_update_edgeTag(MMG5_pTetra pt,MMG5_pxTetra pxt,MMG5_int np, MMG5_int
   int      i,j;
   MMG5_int p0,p1;
   uint8_t  ia,iav;
-  int16_t  tag,tag1;
+  uint16_t tag,tag1;
 
   /* update tags for edges */
   for ( j=0; j<3; j++ ) {
@@ -1010,11 +1010,11 @@ void MMG3D_update_edgeTag(MMG5_pTetra pt,MMG5_pxTetra pxt,MMG5_int np, MMG5_int
  */
 static inline
 MMG5_int MMG3D_update_shellEdgeTag_oneDir(MMG5_pMesh  mesh,MMG5_int start, MMG5_int na, MMG5_int nb,
-                                     int16_t tag,MMG5_int ref, MMG5_int piv,MMG5_int adj) {
+                                     uint16_t tag,MMG5_int ref, MMG5_int piv,MMG5_int adj) {
   MMG5_pTetra  pt;
   MMG5_pxTetra pxt;
   MMG5_int     *adja;
-  int16_t      xtag;
+  uint16_t     xtag;
   int8_t       i;
 
   assert ( tag & MG_BDY && "Unexpected non boundary tag");
@@ -1074,11 +1074,11 @@ MMG5_int MMG3D_update_shellEdgeTag_oneDir(MMG5_pMesh  mesh,MMG5_int start, MMG5_
  *
  */
 static inline
-int MMG3D_update_shellEdgeTag(MMG5_pMesh  mesh,MMG5_int start, int8_t ia,int16_t tag,MMG5_int ref) {
+int MMG3D_update_shellEdgeTag(MMG5_pMesh  mesh,MMG5_int start, int8_t ia,uint16_t tag,MMG5_int ref) {
   MMG5_pTetra  pt;
   MMG5_pxTetra pxt;
   MMG5_int     piv,na,nb,adj,*adja;
-  int16_t      xtag;
+  uint16_t     xtag;
 
   pt   = &mesh->tetra[start];
 
@@ -1278,9 +1278,9 @@ MMG5_int MMG5_colver(MMG5_pMesh mesh,MMG5_pSol met,int64_t *list,int ilist,int8_
       int iped = coled[l+0];
       int iqed = coled[l+1];
 
-      int16_t  tagip = 0;
+      uint16_t tagip = 0;
       MMG5_int refip = 0;
-      int16_t  tagiq = 0;
+      uint16_t tagiq = 0;
       MMG5_int refiq = 0;
 
       if ( !MMG3D_get_shellEdgeTag(mesh,iel,iped,&tagip,&refip) ) {
diff --git a/src/mmg3d/hash_3d.c b/src/mmg3d/hash_3d.c
index 6c3fe3bfc..f0cfef171 100644
--- a/src/mmg3d/hash_3d.c
+++ b/src/mmg3d/hash_3d.c
@@ -615,7 +615,7 @@ int MMG5_setEdgeNmTag(MMG5_pMesh mesh, MMG5_Hash *hash) {
 
 
 static inline
-int MMG5_skip_ParBdy ( int8_t tag ) {
+uint16_t MMG5_skip_ParBdy ( uint16_t tag ) {
   return (tag & MG_PARBDY);
 }
 
@@ -634,7 +634,7 @@ int MMG5_skip_ParBdy ( int8_t tag ) {
  * points to not break the ParMmg distributed analysis in which this field is
  * used to store the global numbering of nodes.
  */
-int MMG5_setVertexNmTag(MMG5_pMesh mesh,int func(int8_t) ) {
+int MMG5_setVertexNmTag(MMG5_pMesh mesh,uint16_t func(uint16_t) ) {
   MMG5_pTetra         ptet;
   MMG5_pPoint         ppt0,ppt1;
   MMG5_Hash           hash;
@@ -911,7 +911,7 @@ int MMG5_hashPop(MMG5_Hash *hash,MMG5_int a,MMG5_int b) {
  * set tag to edge on geometry
  *
  */
-int MMG5_hTag(MMG5_HGeom *hash,MMG5_int a,MMG5_int b,MMG5_int ref,int16_t tag) {
+int MMG5_hTag(MMG5_HGeom *hash,MMG5_int a,MMG5_int b,MMG5_int ref,uint16_t tag) {
   MMG5_hgeom  *ph;
   MMG5_int    key;
   MMG5_int    ia,ib;
@@ -944,7 +944,7 @@ int MMG5_hTag(MMG5_HGeom *hash,MMG5_int a,MMG5_int b,MMG5_int ref,int16_t tag) {
 }
 
 /** remove edge from hash table */
-int MMG5_hPop(MMG5_HGeom *hash,MMG5_int a,MMG5_int b,MMG5_int *ref,int16_t *tag) {
+int MMG5_hPop(MMG5_HGeom *hash,MMG5_int a,MMG5_int b,MMG5_int *ref,uint16_t *tag) {
   MMG5_hgeom  *ph,*php;
   MMG5_int    key;
   MMG5_int    ia,ib,iph,iphp;
@@ -1004,7 +1004,7 @@ int MMG5_hPop(MMG5_HGeom *hash,MMG5_int a,MMG5_int b,MMG5_int *ref,int16_t *tag)
 }
 
 /** get ref and tag to edge on geometry */
-int MMG5_hGet(MMG5_HGeom *hash,MMG5_int a,MMG5_int b,MMG5_int *ref,int16_t *tag) {
+int MMG5_hGet(MMG5_HGeom *hash,MMG5_int a,MMG5_int b,MMG5_int *ref,uint16_t *tag) {
   MMG5_hgeom  *ph;
   MMG5_int    key;
   MMG5_int    ia,ib;
@@ -1037,7 +1037,7 @@ int MMG5_hGet(MMG5_HGeom *hash,MMG5_int a,MMG5_int b,MMG5_int *ref,int16_t *tag)
 }
 
 /** store edge on geometry */
-int MMG5_hEdge(MMG5_pMesh mesh,MMG5_HGeom *hash,MMG5_int a,MMG5_int b,MMG5_int ref,int16_t tag) {
+int MMG5_hEdge(MMG5_pMesh mesh,MMG5_HGeom *hash,MMG5_int a,MMG5_int b,MMG5_int ref,uint16_t tag) {
   MMG5_hgeom  *ph;
   MMG5_int    key;
   MMG5_int    ia,ib,j;
@@ -1114,7 +1114,7 @@ int MMG5_hGeom(MMG5_pMesh mesh) {
   MMG5_Hash    hash;
   MMG5_int     edg,*adja,k,kk;
   int          ier;
-  int16_t      tag;
+  uint16_t     tag;
   int8_t       i,i1,i2;
 
   /* if edges exist in mesh, hash special edges from existing field */
@@ -1964,7 +1964,7 @@ int MMG5_bdrySet(MMG5_pMesh mesh) {
   MMG5_Hash     hash;
   MMG5_int      ref,*adja,adj,k,ia,ib,ic,kt,initedg[3];
   int           j;
-  int16_t       tag,inittag[3];
+  uint16_t      tag,inittag[3];
   int8_t        i,i1,i2;
 
   if ( !mesh->nt )  return 1;
@@ -2002,6 +2002,7 @@ int MMG5_bdrySet(MMG5_pMesh mesh) {
     for (k=1; k<=mesh->ne; k++) {
       pt = &mesh->tetra[k];
       if ( !MG_EOK(pt) )  continue;
+      if (pt->tag & MG_OVERLAP) continue;
       adja = &mesh->adja[4*(k-1)+1];
       for (i=0; i<4; i++) {
         adj = adja[i] / 4;
@@ -2046,6 +2047,7 @@ int MMG5_bdrySet(MMG5_pMesh mesh) {
     for (k=1; k<=mesh->ne; k++) {
       pt = &mesh->tetra[k];
       if ( !MG_EOK(pt) )  continue;
+      if (pt->tag & MG_OVERLAP) continue;
 
       for (i=0; i<4; i++) {
         ia = pt->v[MMG5_idir[i][0]];
@@ -2090,6 +2092,7 @@ int MMG5_bdrySet(MMG5_pMesh mesh) {
     for (k=1; k<=mesh->ne; k++) {
       pt = &mesh->tetra[k];
       if ( !MG_EOK(pt) )  continue;
+      if (pt->tag & MG_OVERLAP) continue;
       if ( !pt->xt )  continue;
       pxt = &mesh->xtetra[pt->xt];
       adja = &mesh->adja[4*(k-1)+1];
@@ -2131,6 +2134,7 @@ int MMG5_bdrySet(MMG5_pMesh mesh) {
     for (k=1; k<=mesh->ne; k++) {
       pt = &mesh->tetra[k];
       if ( !MG_EOK(pt) )  continue;
+      if (pt->tag & MG_OVERLAP) continue;
       if ( !pt->xt )  continue;
       pxt = &mesh->xtetra[pt->xt];
       adja = &mesh->adja[4*(k-1)+1];
@@ -2294,7 +2298,7 @@ int MMG5_bdryUpdate(MMG5_pMesh mesh) {
   MMG5_Hash     hash;
   MMG5_int      ia,ib,ic,k,kt;
   int           j;
-  int16_t       tag;
+  uint16_t      tag;
   int8_t        i;
 
   if ( !mesh->nt )  return 1;
diff --git a/src/mmg3d/intmet_3d.c b/src/mmg3d/intmet_3d.c
index 11b9693d5..27b5fd410 100644
--- a/src/mmg3d/intmet_3d.c
+++ b/src/mmg3d/intmet_3d.c
@@ -94,7 +94,7 @@ int MMG5_intmet_ani(MMG5_pMesh mesh,MMG5_pSol met,MMG5_int k,int8_t i,MMG5_int i
   // explicitely added if we arrive from a boundary face and a boundary edge
   // should not be splitted from a non boundary face
   if ( mesh->adja ) {
-    int16_t  tag = 0;
+    uint16_t tag = 0;
     MMG5_int ref = 0;
     if ( !MMG3D_get_shellEdgeTag(mesh,k,i,&tag,&ref) ) {
       fprintf(stderr,"\n  ## Warning: %s: 0. unable to get edge info"
diff --git a/src/mmg3d/libmmg3d_private.h b/src/mmg3d/libmmg3d_private.h
index ce8a64993..9c298d1ca 100644
--- a/src/mmg3d/libmmg3d_private.h
+++ b/src/mmg3d/libmmg3d_private.h
@@ -224,7 +224,7 @@ int  MMG3D_Free_all_var( va_list argptr );
 int  MMG3D_Free_structures_var( va_list argptr );
 int  MMG3D_Free_names_var( va_list argptr );
 void MMG3D_Free_arrays(MMG5_pMesh*,MMG5_pSol*,MMG5_pSol*,MMG5_pSol*,MMG5_pSol*);
-MMG5_int  MMG3D_newPt(MMG5_pMesh mesh,double c[3],int16_t tag,MMG5_int src);
+MMG5_int  MMG3D_newPt(MMG5_pMesh mesh,double c[3],uint16_t tag,MMG5_int src);
 MMG5_int  MMG3D_newElt(MMG5_pMesh mesh);
 int  MMG3D_delElt(MMG5_pMesh mesh,MMG5_int iel);
 void MMG3D_delPt(MMG5_pMesh mesh,MMG5_int ip);
@@ -271,11 +271,11 @@ void MMG3D_coquilFaceSecondLoopInit(MMG5_pMesh mesh,MMG5_int piv,int8_t *iface,i
 void MMG5_coquilFaceErrorMessage(MMG5_pMesh mesh, MMG5_int k1, MMG5_int k2);
 int16_t MMG5_coquilTravel(MMG5_pMesh,MMG5_int,MMG5_int,MMG5_int*,MMG5_int*,int8_t*,int8_t*);
 int16_t MMG5_openCoquilTravel(MMG5_pMesh,MMG5_int,MMG5_int,MMG5_int*,MMG5_int*,int8_t*,int8_t*);
-int  MMG3D_get_shellEdgeTag(MMG5_pMesh,MMG5_int,int8_t,int16_t*,MMG5_int *);
-int  MMG5_settag(MMG5_pMesh,MMG5_int,int,int16_t,int);
-int  MMG5_deltag(MMG5_pMesh,MMG5_int,int,int16_t);
+int  MMG3D_get_shellEdgeTag(MMG5_pMesh,MMG5_int,int8_t,uint16_t*,MMG5_int *);
+int  MMG5_settag(MMG5_pMesh,MMG5_int,int,uint16_t,int);
+int  MMG5_deltag(MMG5_pMesh,MMG5_int,int,uint16_t);
 int  MMG5_setNmTag(MMG5_pMesh mesh, MMG5_Hash *hash);
-int  MMG5_setVertexNmTag(MMG5_pMesh mesh,int func(int8_t) );
+int  MMG5_setVertexNmTag(MMG5_pMesh mesh,uint16_t func(uint16_t) );
 int  MMG5_chkcol_int(MMG5_pMesh,MMG5_pSol,MMG5_int,int8_t,int8_t,int64_t*,int,int8_t);
 int  MMG5_chkcol_bdy(MMG5_pMesh,MMG5_pSol,MMG5_int,int8_t,int8_t,int64_t*,int,MMG5_int*,int,MMG5_int,MMG5_int,int8_t,int,int8_t);
 int  MMG3D_chkmanicoll(MMG5_pMesh,MMG5_int,int,int,MMG5_int,MMG5_int,MMG5_int,MMG5_int,int8_t,int8_t);
@@ -295,10 +295,10 @@ MMG5_int  MMG5_hashGetFace(MMG5_Hash*,MMG5_int,MMG5_int,MMG5_int);
 int  MMG3D_hashTria(MMG5_pMesh mesh, MMG5_Hash*);
 int  MMG3D_hashPrism(MMG5_pMesh mesh);
 int  MMG5_hashPop(MMG5_Hash *hash,MMG5_int a,MMG5_int b);
-int  MMG5_hPop(MMG5_HGeom *hash,MMG5_int a,MMG5_int b,MMG5_int *ref,int16_t *tag);
-int  MMG5_hTag(MMG5_HGeom *hash,MMG5_int a,MMG5_int b,MMG5_int ref,int16_t tag);
-int  MMG5_hGet(MMG5_HGeom *hash,MMG5_int a,MMG5_int b,MMG5_int *ref,int16_t *tag);
-int  MMG5_hEdge(MMG5_pMesh mesh,MMG5_HGeom *hash,MMG5_int a,MMG5_int b,MMG5_int ref,int16_t tag);
+int  MMG5_hPop(MMG5_HGeom *hash,MMG5_int a,MMG5_int b,MMG5_int *ref,uint16_t *tag);
+int  MMG5_hTag(MMG5_HGeom *hash,MMG5_int a,MMG5_int b,MMG5_int ref,uint16_t tag);
+int  MMG5_hGet(MMG5_HGeom *hash,MMG5_int a,MMG5_int b,MMG5_int *ref,uint16_t *tag);
+int  MMG5_hEdge(MMG5_pMesh mesh,MMG5_HGeom *hash,MMG5_int a,MMG5_int b,MMG5_int ref,uint16_t tag);
 int  MMG5_hNew(MMG5_pMesh mesh,MMG5_HGeom *hash,MMG5_int hsiz,MMG5_int hmax);
 int  MMG5_hGeom(MMG5_pMesh mesh);
 int  MMG5_bdryIso(MMG5_pMesh );
@@ -318,6 +318,7 @@ int  MMG3D_resetRef_ls(MMG5_pMesh mesh);
 int  MMG3D_resetRef_lssurf(MMG5_pMesh mesh);
 int  MMG3D_setref_ls(MMG5_pMesh mesh, MMG5_pSol sol);
 int  MMG3D_setref_lssurf(MMG5_pMesh mesh, MMG5_pSol sol);
+int  MMG3D_ismaniball(MMG5_pMesh mesh,MMG5_pSol sol,MMG5_int k,int indp);
 int  MMG3D_snpval_ls(MMG5_pMesh mesh,MMG5_pSol sol);
 int  MMG3D_snpval_lssurf(MMG5_pMesh mesh,MMG5_pSol sol);
 int  MMG3D_cuttet_ls(MMG5_pMesh mesh, MMG5_pSol sol,MMG5_pSol met);
@@ -368,7 +369,7 @@ int    MMG5_movbdyregpt_iso(MMG5_pMesh, MMG5_pSol,MMG3D_pPROctree,
                              int64_t*, int, MMG5_int*, int, int ,int);
 int    MMG5_movbdyregpt_ani(MMG5_pMesh, MMG5_pSol,MMG3D_pPROctree,
                              int64_t*, int, MMG5_int*, int, int ,int);
-int MMG3D_curveEndingPts(MMG5_pMesh,MMG5_int*,int,const int16_t,MMG5_int,MMG5_int*,MMG5_int*);
+int MMG3D_curveEndingPts(MMG5_pMesh,MMG5_int*,int,const uint16_t,MMG5_int,MMG5_int*,MMG5_int*);
 int MMG3D_movbdycurvept_chckAndUpdate(MMG5_pMesh mesh, MMG5_pSol met,
                                       MMG3D_pPROctree PROctree, int64_t *listv,
                                       int ilistv,int improve,MMG5_pPoint p0,
@@ -377,7 +378,7 @@ int MMG3D_movbdycurvept_chckAndUpdate(MMG5_pMesh mesh, MMG5_pSol met,
 int MMG3D_movbdycurvept_newPosForSimu(MMG5_pMesh,MMG5_pPoint,MMG5_int,MMG5_int,MMG5_int,
                                       double,double,uint8_t,const double,
                                       double[3],double[3],
-                                      double[3],double[3],const int16_t);
+                                      double[3],double[3],const uint16_t);
 int    MMG5_movbdyrefpt_iso(MMG5_pMesh, MMG5_pSol,MMG3D_pPROctree, int64_t*, int,
                              MMG5_int*, int ,int);
 int    MMG5_movbdyrefpt_ani(MMG5_pMesh, MMG5_pSol,MMG3D_pPROctree, int64_t*, int,
@@ -467,7 +468,7 @@ void MMG5_printTetra(MMG5_pMesh mesh,char* fileName);
 void MMG3D_chkpointtag(MMG5_pMesh mesh);
 void MMG3D_chkmeshedgestags(MMG5_pMesh mesh);
 void MMG3D_chkfacetags(MMG5_pMesh mesh);
-int MMG3D_chk_shellEdgeTag(MMG5_pMesh  mesh,MMG5_int start, int8_t ia,int16_t tag,MMG5_int ref);
+int MMG3D_chk_shellEdgeTag(MMG5_pMesh  mesh,MMG5_int start, int8_t ia,uint16_t tag,MMG5_int ref);
 
 #ifdef USE_SCOTCH
 int MMG5_mmg3dRenumbering(int,MMG5_pMesh,MMG5_pSol,MMG5_pSol,MMG5_int*);
@@ -493,7 +494,7 @@ int MMG5_cenrad_iso(MMG5_pMesh mesh,double *ct,double *c,double *rad);
 int MMG5_cenrad_ani(MMG5_pMesh mesh,double *ct,double *m,double *c,double *rad);
 
 /* mmg3d1.c */
-void MMG3D_set_geom(MMG5_pMesh,MMG5_pPoint,int16_t,MMG5_int,MMG5_int,double[3],double[3],double[3]);
+void MMG3D_set_geom(MMG5_pMesh,MMG5_pPoint,uint16_t,MMG5_int,MMG5_int,double[3],double[3],double[3]);
 void MMG5_tet2tri(MMG5_pMesh mesh,MMG5_int k,int8_t ie,MMG5_Tria *ptt);
 int  MMG3D_dichoto(MMG5_pMesh mesh,MMG5_pSol met,MMG5_int k,MMG5_int *vx);
 int  MMG3D_dichoto1b(MMG5_pMesh mesh,MMG5_pSol met,int64_t *list,int ret,MMG5_int);
@@ -502,7 +503,7 @@ void MMG3D_find_bdyface_from_edge(MMG5_pMesh,MMG5_pTetra,int8_t,int8_t*,int8_t*,
                                   int8_t*,int8_t*,MMG5_int*,MMG5_int*,MMG5_pPoint*,MMG5_pPoint*);
 int8_t MMG3D_build_bezierEdge(MMG5_pMesh,MMG5_int,int8_t,int8_t,int8_t,MMG5_pxTetra,
                               MMG5_int,MMG5_int,MMG5_pPoint,MMG5_pPoint,
-                              MMG5_int*,int16_t*,double[3],double[3],double[3],
+                              MMG5_int*,uint16_t*,double[3],double[3],double[3],
                               double[3],int64_t*,int*);
 int MMG3D_adpcoledg(MMG5_pMesh,MMG5_pSol,MMG3D_pPROctree*,MMG5_int,int8_t,double,MMG5_int*);
 int  MMG3D_splsurfedge( MMG5_pMesh,MMG5_pSol,MMG5_int,MMG5_pTetra,MMG5_pxTetra,int8_t,
diff --git a/src/mmg3d/mmg3d1.c b/src/mmg3d/mmg3d1.c
index 7232ad096..dc005e3c7 100644
--- a/src/mmg3d/mmg3d1.c
+++ b/src/mmg3d/mmg3d1.c
@@ -57,7 +57,7 @@ extern int8_t ddb;
  *
  */
 void MMG3D_set_geom(MMG5_pMesh mesh, MMG5_pPoint ppt,
-                    int16_t tag,MMG5_int nmref,MMG5_int edgref,
+                    uint16_t tag,MMG5_int nmref,MMG5_int edgref,
                     double no1[3],double no2[3],double to[3]) {
 
   if ( MG_EDG_OR_NOM(tag) ) {
@@ -899,7 +899,10 @@ static MMG5_int MMG5_coltet(MMG5_pMesh mesh,MMG5_pSol met,int8_t typchk) {
   MMG5_int        base,k,nc,nnm,lists[MMG3D_LMAX+2],refmin,refplus;
   int64_t         list[MMG3D_LMAX+2];
   int             l,kk,isloc,ifac1;
-  int16_t         tag,tag0,tag1,isnm,isnmint;
+
+  uint16_t        tag,tag0,tag1,isnm;
+  int16_t         isnmint;
+
   int8_t          i,j,ip,iq;
   int             ier, bsret;   // function return values/error codes
 
@@ -938,10 +941,11 @@ static MMG5_int MMG5_coltet(MMG5_pMesh mesh,MMG5_pSol met,int8_t typchk) {
         }
         else {
           /* Ignore OLDPARBDY tag of p0 */
-          int16_t tag0 = p0->tag, tag1 = p1->tag;
+          uint16_t tag0 = p0->tag, tag1 = p1->tag;
           tag0 &= ~MG_OLDPARBDY;
           tag1 &= ~MG_OLDPARBDY;
           if ( (tag0 > tag1) || (tag0 & MG_REQ) ) {
+
             /* Unable to merge edge */
             continue;
           }
@@ -1231,7 +1235,7 @@ int MMG3D_adpcoledg(MMG5_pMesh mesh, MMG5_pSol met,
   MMG3D_find_bdyface_from_edge(mesh,pt,imin,&i,&j,&i1,&i2,&ip1,&ip2,&p0,&p1);
 
   /* Ignore OLDPARBDY tag of p0 */
-  int16_t tag0 = p0->tag;
+  uint16_t tag0 = p0->tag;
   tag0 &= ~MG_OLDPARBDY;
   if ( (tag0 > p1->tag) || (tag0 & MG_REQ) ) {
     /* Unable to merge edge: pass to next element */
@@ -1242,7 +1246,7 @@ int MMG3D_adpcoledg(MMG5_pMesh mesh, MMG5_pSol met,
   ilist = 0;
   if ( pt->xt && (pxt->ftag[i] & MG_BDY) ) {
     /* Case of a boundary face */
-    int16_t tag = pxt->tag[MMG5_iarf[i][j]];
+    uint16_t tag = pxt->tag[MMG5_iarf[i][j]];
     if ( tag & MG_REQ ) {
       return 0;
     }
@@ -1255,7 +1259,7 @@ int MMG3D_adpcoledg(MMG5_pMesh mesh, MMG5_pSol met,
       return 0;
     }
 
-    int16_t isnm = (p0->tag & MG_NOM);
+    uint16_t isnm = (p0->tag & MG_NOM);
     if (MMG5_boulesurfvolp(mesh,k,i1,i, list,&ilist,lists,&ilists,isnm) < 0 ) {
       return -1;
     }
@@ -1778,7 +1782,7 @@ int8_t MMG3D_build_bezierEdge(MMG5_pMesh mesh,MMG5_int k,
                               MMG5_pxTetra pxt,
                               MMG5_int ip1,MMG5_int ip2,
                               MMG5_pPoint p0, MMG5_pPoint p1,
-                              MMG5_int *ref,int16_t *tag,
+                              MMG5_int *ref,uint16_t *tag,
                               double o[3],double to[3],double no1[3],
                               double no2[3],int64_t *list,int *ilist) {
   MMG5_Tria    ptt;
@@ -1959,7 +1963,7 @@ int MMG3D_splsurfedge( MMG5_pMesh mesh,MMG5_pSol met,MMG5_int k,
   MMG5_int     src,ip,ip1,ip2,ref;
   int64_t      list[MMG3D_LMAX+2];
   int          ier;
-  int16_t      tag;
+  uint16_t     tag;
   int8_t       j,i,i1,i2;
 
   assert ( pxt == &mesh->xtetra[pt->xt] && "suitable xtetra assignation" );
diff --git a/src/mmg3d/mmg3d1_delone.c b/src/mmg3d/mmg3d1_delone.c
index fd67a6fdd..62911114b 100644
--- a/src/mmg3d/mmg3d1_delone.c
+++ b/src/mmg3d/mmg3d1_delone.c
@@ -112,7 +112,7 @@ int MMG3D_mmg3d1_delone_split(MMG5_pMesh mesh, MMG5_pSol met,
     /* Construction of bezier edge */
     double      to[3],no1[3],no2[3];
     MMG5_int    ref;
-    int16_t     tag;
+    uint16_t    tag;
     MMG5_pPoint ppt;
 
     int8_t ier = MMG3D_build_bezierEdge(mesh,k,imax,i,j,pxt,ip1,ip2,p0,p1,
diff --git a/src/mmg3d/mmg3d2.c b/src/mmg3d/mmg3d2.c
index 107763935..094f96b4e 100644
--- a/src/mmg3d/mmg3d2.c
+++ b/src/mmg3d/mmg3d2.c
@@ -404,8 +404,7 @@ MMG5_invsl(double A[3][3],double b[3],double r[3]) {
  *
  */
 
-static int
-MMG3D_ismaniball(MMG5_pMesh mesh,MMG5_pSol sol,MMG5_int k,int indp) {
+int MMG3D_ismaniball(MMG5_pMesh mesh,MMG5_pSol sol,MMG5_int k,int indp) {
   MMG5_pTetra   pt,pt1;
   double        v,v0,v1,v2;
   int           ibdy,ilist,cur,l;
diff --git a/src/mmg3d/mmg3d3.c b/src/mmg3d/mmg3d3.c
index 23d247ce6..ede42ad99 100644
--- a/src/mmg3d/mmg3d3.c
+++ b/src/mmg3d/mmg3d3.c
@@ -143,7 +143,7 @@ static MMG5_int MMG5_spllag(MMG5_pMesh mesh,MMG5_pSol disp,MMG5_pSol met,int itd
       if ( pxt && (pxt->tag[i] & MG_BDY) )  continue;
 
       // Slower test but allowing to be sure to detect boundary edges
-      int16_t  tag = 0;
+      uint16_t  tag = 0;
       MMG5_int ref = 0;
       if ( !MMG3D_get_shellEdgeTag(mesh,k,i,&tag,&ref) ) {
         fprintf(stderr,"\n  ## Warning: %s: 0. unable to get edge info"
diff --git a/src/mmg3d/movpt_3d.c b/src/mmg3d/movpt_3d.c
index 3318674b6..2954aa2e9 100644
--- a/src/mmg3d/movpt_3d.c
+++ b/src/mmg3d/movpt_3d.c
@@ -851,11 +851,11 @@ int MMG5_movbdyregpt_iso(MMG5_pMesh mesh, MMG5_pSol met, MMG3D_pPROctree PROctre
  */
 static inline
 int MMG3D_curveEndingPts_chkEdg(MMG5_pMesh mesh,MMG5_int *lists,int l,MMG5_int ip0,
-                                MMG5_int *ipa,MMG5_int *ipb,const int16_t edgTag,MMG5_int *ip) {
+                                MMG5_int *ipa,MMG5_int *ipb,const uint16_t edgTag,MMG5_int *ip) {
 
   MMG5_pTetra           pt;
   MMG5_int              iel,iptmpa,iptmpb;
-  int16_t               tag;
+  uint16_t              tag;
   uint8_t               i,ie,iface,iea,ieb;
 
   iel   = lists[l] / 4;
@@ -942,7 +942,7 @@ int MMG3D_curveEndingPts_chkEdg(MMG5_pMesh mesh,MMG5_int *lists,int l,MMG5_int i
  * other direction until meeting the second curve edge.
  */
 int MMG3D_curveEndingPts(MMG5_pMesh mesh,MMG5_int *lists,int ilists,
-                         const int16_t edgTag, MMG5_int ip0,MMG5_int *ip1,
+                         const uint16_t edgTag, MMG5_int ip0,MMG5_int *ip1,
                          MMG5_int *ip2) {
   MMG5_pTetra           pt;
   MMG5_int              iel,ipa,ipb;
@@ -1152,7 +1152,7 @@ int MMG3D_movbdycurvept_newPosForSimu(MMG5_pMesh mesh,MMG5_pPoint p0,MMG5_int ip
                                       uint8_t isrid,const double step,
                                       double o[3],double no[3],
                                       double no2[3],double to[3],
-                                      const int16_t edgTag) {
+                                      const uint16_t edgTag) {
 
   MMG5_int ip;
 
diff --git a/src/mmg3d/split_3d.c b/src/mmg3d/split_3d.c
index fbbe0a6ac..d48af88c3 100644
--- a/src/mmg3d/split_3d.c
+++ b/src/mmg3d/split_3d.c
@@ -4921,7 +4921,7 @@ MMG5_int MMG5_splitedg(MMG5_pMesh mesh, MMG5_pSol met,MMG5_int iel, int iar, dou
   int          warn,lon,ier;
   int64_t      list[MMG3D_LMAX+2];
   MMG5_int     src,i0,i1,ip;
-  int16_t      tag;
+  uint16_t     tag;
 
   warn = 0;
   pt = &mesh->tetra[iel];
diff --git a/src/mmg3d/swap_3d.c b/src/mmg3d/swap_3d.c
index 3102816ae..fc3c6f70b 100644
--- a/src/mmg3d/swap_3d.c
+++ b/src/mmg3d/swap_3d.c
@@ -348,7 +348,7 @@ int MMG5_chkswpbdy(MMG5_pMesh mesh, MMG5_pSol met, int64_t *list,int ilist,
 
 #ifndef NDEBUG
   /* Security check: ensure that the edge is boundary */
-  int16_t  tag = 0;
+  uint16_t  tag = 0;
   MMG5_int ref = 0;
   if ( !MMG3D_get_shellEdgeTag(mesh,list[0]/6,list[0]%6,&tag,&ref) ) {
     fprintf(stderr,"\n  ## Warning: %s: 0. unable to get edge info"
diff --git a/src/mmg3d/zaldy_3d.c b/src/mmg3d/zaldy_3d.c
index c062f4d18..d6129246c 100644
--- a/src/mmg3d/zaldy_3d.c
+++ b/src/mmg3d/zaldy_3d.c
@@ -36,7 +36,7 @@
 #include "libmmg3d_private.h"
 
 /** get new point address */
-MMG5_int MMG3D_newPt(MMG5_pMesh mesh,double c[3],int16_t tag,MMG5_int src) {
+MMG5_int MMG3D_newPt(MMG5_pMesh mesh,double c[3],uint16_t tag,MMG5_int src) {
 
   MMG5_pPoint  ppt;
   MMG5_int     curpt;
@@ -63,7 +63,7 @@ MMG5_int MMG3D_newPt(MMG5_pMesh mesh,double c[3],int16_t tag,MMG5_int src) {
     }
     ppt->xp  = mesh->xp;
   }
-  assert(tag < 24704);
+  assert(tag <= MG_NUL*2-1 && "Value for tag is valid");
   assert(tag >= 0);
   ppt->n[0]   = 0;
   ppt->n[1]   = 0;
diff --git a/src/mmgs/analys_s.c b/src/mmgs/analys_s.c
index 4fa8259a3..75adaa877 100644
--- a/src/mmgs/analys_s.c
+++ b/src/mmgs/analys_s.c
@@ -48,7 +48,7 @@ int MMGS_setadj(MMG5_pMesh mesh){
   MMG5_pTria   pt,pt1;
   MMG5_int     *adja,*adjb,adji1,adji2,*pile,iad,ipil,ip1,ip2,gen;
   MMG5_int     k,kk,iel,jel,nvf,nf,nr,nt,nre,nreq,ncc,ned,ref;
-  int16_t      tag;
+  uint16_t     tag;
   int8_t       i,ii,i1,i2,ii1,ii2,voy;
 
   if ( abs(mesh->info.imprim) > 5  || mesh->info.ddebug )
diff --git a/src/mmgs/hash_s.c b/src/mmgs/hash_s.c
index fce1a2567..041b049b6 100644
--- a/src/mmgs/hash_s.c
+++ b/src/mmgs/hash_s.c
@@ -170,7 +170,7 @@ int MMGS_bdryUpdate(MMG5_pMesh mesh) {
   MMG5_Hash   hash;
   MMG5_pTria  pt;
   MMG5_int    k,nad;
-  int         tag;
+  uint16_t    tag;
   int8_t      i,i1,i2;
 
   /* adjust hash table params */