diff --git a/src/aig/gia/gia.h b/src/aig/gia/gia.h
index 803fff514..1069f5d20 100644
--- a/src/aig/gia/gia.h
+++ b/src/aig/gia/gia.h
@@ -201,9 +201,9 @@ struct Gia_ParSim_t_
 typedef struct Gia_ParVta_t_ Gia_ParVta_t;
 struct Gia_ParVta_t_
 {
-    int            nFramesStart;  // starting frame 
     int            nFramesMax;    // maximum frames
-    int            nFramesOver;   // overlap frames
+    int            nFramesStart;  // starting frame 
+    int            nFramesPast;   // overlap frames
     int            nConfLimit;    // conflict limit
     int            nTimeOut;      // timeout in seconds
     int            nRatioMin;     // stop when less than this % of object is abstracted
diff --git a/src/aig/gia/giaAbsVta.c b/src/aig/gia/giaAbsVta.c
index 09ed91ab5..d406b3cea 100644
--- a/src/aig/gia/giaAbsVta.c
+++ b/src/aig/gia/giaAbsVta.c
@@ -145,13 +145,13 @@ extern void Vga_ManAddClausesOne( Vta_Man_t * p, int iObj, int iFrame );
 void Gia_VtaSetDefaultParams( Gia_ParVta_t * p )
 {
     memset( p, 0, sizeof(Gia_ParVta_t) );
-    p->nFramesStart  =    5;   // starting frame 
-    p->nFramesOver   =    4;   // overlap frames
     p->nFramesMax    =    0;   // maximum frames
+    p->nFramesStart  =    5;   // starting frame 
+    p->nFramesPast   =    4;   // overlap frames
     p->nConfLimit    =    0;   // conflict limit
     p->nTimeOut      =    0;   // timeout in seconds
     p->nRatioMin     =   10;   // stop when less than this % of object is abstracted
-    p->fUseTermVars  =    0;   // use terminal variables
+    p->fUseTermVars  =    1;   // use terminal variables
     p->fVerbose      =    0;   // verbose flag
     p->iFrame        =   -1;   // the number of frames covered 
 }
@@ -1409,7 +1409,7 @@ int Gia_VtaPerform( Gia_Man_t * pAig, Gia_ParVta_t * pPars )
     {
         printf( "Running variable-timeframe abstraction (VTA) with the following parameters:\n" );
         printf( "FrameStart = %d  FramePast = %d  FrameMax = %d  Conf = %d  Timeout = %d. RatioMin = %d %%.\n", 
-            p->pPars->nFramesStart, p->pPars->nFramesOver, p->pPars->nFramesMax, 
+            p->pPars->nFramesStart, p->pPars->nFramesPast, p->pPars->nFramesMax, 
             p->pPars->nConfLimit, p->pPars->nTimeOut, pPars->nRatioMin );
         printf( "Frame   Abs   Confl  Cex   Core   F0   F1   F2   F3  ...\n" );
     }
@@ -1435,7 +1435,7 @@ int Gia_VtaPerform( Gia_Man_t * pAig, Gia_ParVta_t * pPars )
             sat_solver2_bookmark( p->pSat );
             Vec_IntClear( p->vAddedNew );
             // load the time frame
-            for ( i = 1; i <= Abc_MinInt(p->pPars->nFramesOver, p->pPars->nFramesStart); i++ )
+            for ( i = 1; i <= Abc_MinInt(p->pPars->nFramesPast, p->pPars->nFramesStart); i++ )
                 Vga_ManLoadSlice( p, (Vec_Int_t *)Vec_PtrEntry(p->vCores, f-i), i );
             // iterate as long as there are counter-examples
             for ( i = 0; ; i++ )
diff --git a/src/base/abci/abc.c b/src/base/abci/abc.c
index 6b8f117b4..17c579662 100644
--- a/src/base/abci/abc.c
+++ b/src/base/abci/abc.c
@@ -26711,21 +26711,10 @@ int Abc_CommandAbc9Vta( Abc_Frame_t * pAbc, int argc, char ** argv )
     int c;
     Gia_VtaSetDefaultParams( pPars );
     Extra_UtilGetoptReset();
-    while ( ( c = Extra_UtilGetopt( argc, argv, "SFPCTRtvh" ) ) != EOF )
+    while ( ( c = Extra_UtilGetopt( argc, argv, "FSPCTRtvh" ) ) != EOF )
     {
         switch ( c )
         {
-        case 'S':
-            if ( globalUtilOptind >= argc )
-            {
-                Abc_Print( -1, "Command line switch \"-S\" should be followed by an integer.\n" );
-                goto usage;
-            }
-            pPars->nFramesStart = atoi(argv[globalUtilOptind]);
-            globalUtilOptind++;
-            if ( pPars->nFramesStart < 0 ) 
-                goto usage;
-            break;
         case 'F':
             if ( globalUtilOptind >= argc )
             {
@@ -26737,15 +26726,26 @@ int Abc_CommandAbc9Vta( Abc_Frame_t * pAbc, int argc, char ** argv )
             if ( pPars->nFramesMax < 0 ) 
                 goto usage;
             break;
+        case 'S':
+            if ( globalUtilOptind >= argc )
+            {
+                Abc_Print( -1, "Command line switch \"-S\" should be followed by an integer.\n" );
+                goto usage;
+            }
+            pPars->nFramesStart = atoi(argv[globalUtilOptind]);
+            globalUtilOptind++;
+            if ( pPars->nFramesStart < 0 ) 
+                goto usage;
+            break;
         case 'P':
             if ( globalUtilOptind >= argc )
             {
                 Abc_Print( -1, "Command line switch \"-P\" should be followed by an integer.\n" );
                 goto usage;
             }
-            pPars->nFramesOver = atoi(argv[globalUtilOptind]);
+            pPars->nFramesPast = atoi(argv[globalUtilOptind]);
             globalUtilOptind++;
-            if ( pPars->nFramesOver < 0 ) 
+            if ( pPars->nFramesPast < 0 ) 
                 goto usage;
             break;
         case 'C':
@@ -26824,11 +26824,11 @@ int Abc_CommandAbc9Vta( Abc_Frame_t * pAbc, int argc, char ** argv )
     return 0;
 
 usage:
-    Abc_Print( -2, "usage: &vta [-SFPCTR num] [-tvh]\n" );
+    Abc_Print( -2, "usage: &vta [-FSPCTR num] [-tvh]\n" );
     Abc_Print( -2, "\t         refines abstracted object map with proof-based abstraction\n" );
-    Abc_Print( -2, "\t-S num : the starting time frame (0=unused) [default = %d]\n", pPars->nFramesStart );
     Abc_Print( -2, "\t-F num : the max number of timeframes to unroll [default = %d]\n", pPars->nFramesMax );
-    Abc_Print( -2, "\t-P num : the number of previous frames for UNSAT core [default = %d]\n", pPars->nFramesOver );
+    Abc_Print( -2, "\t-S num : the starting time frame (0=unused) [default = %d]\n", pPars->nFramesStart );
+    Abc_Print( -2, "\t-P num : the number of previous frames for UNSAT core [default = %d]\n", pPars->nFramesPast );
     Abc_Print( -2, "\t-C num : the max number of SAT solver conflicts (0=unused) [default = %d]\n", pPars->nConfLimit );
     Abc_Print( -2, "\t-T num : an approximate timeout, in seconds [default = %d]\n", pPars->nTimeOut );
     Abc_Print( -2, "\t-R num : stop when less than this %% of object is abstracted (0<=num<=100) [default = %d]\n", pPars->nRatioMin );