diff --git a/modules/gmt/modgmt_func.cpp b/modules/gmt/modgmt_func.cpp
index 039b687..9d56d2e 100644
--- a/modules/gmt/modgmt_func.cpp
+++ b/modules/gmt/modgmt_func.cpp
@@ -89,54 +89,44 @@ const ObjectBase* GMT_ColorCMYK(const ObjectList* input)
 /*
 Input:
 1) Three arguments, first is Layer, second and third are double. Interprets as new absolute position in cm.
-2) Pairs list. Names are l (layer), x, y, xrel (xr), yrel (yr). Pair with name l may be absent, in this case search in list and using as layer object with ObjectGMTLayer type. x and y are absolute positions in cm, xrel and yrel are shift from current position. x (y) and xrel (yrel) are mutually exlusive, but x (y) and yrel (xrel) can be used simultaneously. If position for some axis is absent, then this position is unchanged.
+2) Pairs list. Names are l (layer), x, y, relx (rx), rely (ry). Pair with name l may be absent, in this case search in list and using as layer object with ObjectGMTLayer type. x and y are absolute positions in cm, relx and rely are shift from current position. x (y) and relx (rely) are mutually exlusive, but x (y) and rely (relx) can be used simultaneously. If position for some axis is absent, then this position is unchanged.
 */
 const ObjectBase* GMT_LayerShift(const ObjectList* input)
 {
- auto size=input->Size();
  struct gmt_layer layer;
+ std::string err;
 
  // Case 1
- if(3==size)
  {
-  Base2Layer l(input,0);
-  Base2Double x(input,1), y(input,2);
-  bool suc=true;
-  layer=l(&suc);
-  if(!suc) goto case2;
-  layer.shiftx=x(&suc);
-  layer.shifty=y(&suc);
-  if(!suc) goto case2;
+  RPosPar<Base2Layer> l("layer");
+  OPosPar<Base2DoubleD> x("x",0.0), y("y",0.0);
+
+  {ParsePositionalParameters params(input,l,x,y); if(!params) goto case2;} // Try case 2, if case 1 failed.
+  layer=l; layer.shiftx=x; layer.shifty=y;
   return new ObjectGMTLayer(layer);
  }
 
  case2:
-
- // Search layer for shifting
- {
-  SearchParameter<struct gmt_layer> original(input,"layer","l");
-  bool suc=true;
-  layer=original(&suc);
-  if(!suc) goto fail; // Conversion failed or too many arguments
- }
- // Do shift
  {
-  BaseM2Double xr(input,"xrel","xr"), yr(input,"yrel","yr");
-  Base2Double x(input,"x"), y(input,"y");
-  bool suc=true;
+  RNPar<Base2Layer> l("layer");
+  ONPar<Base2Double> x("x"),y("y"),rx("r[el]x"),ry("r[el]y");
+
+  {ParseNamedParameters params(input,l,x,y); if(!params) {err=params.Error(); goto fail;}} // Parsing error
+
   // Check duplicate parameters
-  if( ( x.Exist() && xr.Exist() ) || ( y.Exist() && yr.Exist() ) ) goto fail;
-  if(x.Exist()) layer.shiftx=x(&suc);
-  if(y.Exist()) layer.shifty=y(&suc);
-  if(xr.Exist()) layer.shiftx+=x(&suc);
-  if(yr.Exist()) layer.shifty+=y(&suc);
-  if(!suc) goto fail;
+  if(x.Exist() && rx.Exist()) {err="Only one of "+x.Name()+" or "+rx.Name()+" can be specified."; goto fail;}
+  if(y.Exist() && ry.Exist()) {err="Only one of "+y.Name()+" or "+ry.Name()+" can be specified."; goto fail;}
+  // Do shift
+  if( x.Exist()) layer.shiftx=x;
+  if( y.Exist()) layer.shifty=y;
+  if(rx.Exist()) layer.shiftx+=rx;
+  if(ry.Exist()) layer.shifty+=ry;
  }
 
  return new ObjectGMTLayer(layer);
 
  fail:
- return 0;
+ return new ObjectError("LayerShift",err);
 }
 
 
diff --git a/modules/gmt/modgmt_func.h b/modules/gmt/modgmt_func.h
index 8c18e3b..fe5a386 100644
--- a/modules/gmt/modgmt_func.h
+++ b/modules/gmt/modgmt_func.h
@@ -177,9 +177,11 @@ using Base2Color =Base2Struct<struct gmt_color>;
 using Base2Dash  =Base2Struct<struct gmt_dash>;
 using Base2Pen   =Base2Struct<struct gmt_pen>;
 using Base2Font  =Base2Struct<struct gmt_font>;
+using Base2Layer =Base2Struct<struct gmt_layer>;
 
 // Simple aliases of convertors with default values
 using Base2StringD=Base2StructD<std::string>;
+using Base2DoubleD=Base2StructD<double>;
 
 // Specialised convertors
 // Convertor with default value for gmt_coord. Added constructor for creating default value from double argument