diff --git a/idl/idl_api.ysl2 b/idl/idl_api.ysl2
new file mode 100644
index 0000000..f452f1a
--- /dev/null
+++ b/idl/idl_api.ysl2
@@ -0,0 +1,121 @@
+// ----------------------------------------------------------------------
+// stdlib candidates
+// ----------------------------------------------------------------------
+def "func:autocomma" {
+  result if "position()!=last()" > ,
+}
+
+def "func:exists" {
+  param "xpath";
+
+  choose {
+    when "$xpath"
+        result "true()";
+    otherwise
+        result "false()";
+  }
+}
+
+// ----------------------------------------------------------------------
+// idl-api (ysl2)
+// ----------------------------------------------------------------------
+
+def "func:idl_typekind_is_defined" {
+    param "typekind";
+    result "func:exists(/pEpACIDLang/idl/typekinds//*[name()=$typekind])"
+}
+
+def "func:idl_typekind_is_generic" {
+    param "typekind";
+    result "func:exists(/pEpACIDLang/idl/typekinds/generics/*[name()=$typekind])"
+}
+
+def "func:idl_type_is_of_typekind_basetype" {
+    param "idltype";
+    result "func:exists(/pEpACIDLang/idl/basetypes/*[name()=$idltype])";
+}
+
+def "func:idl_type_is_of_typekind_deftype" {
+    param "idltype";
+    result "func:exists(//deftype[@name=$idltype])";
+}
+
+def "func:idl_type_is_of_typekind_enum" {
+    param "idltype";
+    result "func:exists(//enum[@name=$idltype])";
+}
+
+def "func:idl_type_is_of_typekind_struct" {
+    param "idltype";
+    result "func:exists(//struct[@name=$idltype])";
+}
+
+def "func:idl_type_is_of_typekind_list" {
+    param "idltype";
+    result "false()";
+}
+
+def "func:idl_type_is_defined" {
+    param "idltype";
+    choose {
+        when "func:idl_type_get_typekind_of_type($idltype)"
+            result "true()";
+        otherwise
+            result "false()";
+    }
+}
+
+def "func:idl_type_get_typekind_of_type" {
+    param "idltype";
+    choose {
+        when "func:idl_type_is_of_typekind_basetype($idltype)"
+            result > basetype
+        when "func:idl_type_is_of_typekind_deftype($idltype)"
+            result > deftype
+        when "func:idl_type_is_of_typekind_enum($idltype)"
+            result > enum
+        when "func:idl_type_is_of_typekind_struct($idltype)"
+            result > struct
+        when "func:idl_type_is_of_typekind_list($idltype)"
+            result > list
+        otherwise
+            result "false()";
+
+    }
+}
+
+def "func:idl_type_get_resolved_typekind" {
+    param "idltype";
+    const "idltypekind", "func:idl_type_get_typekind_of_type($idltype)";
+
+    choose {
+        when "$idltypekind = 'deftype'"
+            result "func:idl_type_get_typekind_of_type(func:idl_type_get_type_of_deftype($idltype))";
+        otherwise
+            result "$idltypekind";
+    }
+}
+
+def "func:idl_type_get_resolved_type" {
+    param "idltype";
+    const "idltypekind", "func:idl_type_get_typekind_of_type($idltype)";
+
+    choose {
+        when "$idltypekind = 'deftype'"
+            result "func:idl_type_get_type_of_deftype($idltype)";
+        otherwise
+            result "$idltype";
+    }
+}
+
+def "func:idl_type_get_type_of_deftype" {
+    param "idltype";
+    choose {
+        when "func:idl_type_is_of_typekind_deftype($idltype)"
+            result "//deftype[@name=$idltype]/as/@type";
+        otherwise
+            error > idl_resolve_deftype - is not a deftype: «$idltype»;
+    }
+}
+
+
diff --git a/lm-c99/ig-c99.ysl2 b/lm-c99/ig-c99.ysl2
index d17e2ec..211341c 100644
--- a/lm-c99/ig-c99.ysl2
+++ b/lm-c99/ig-c99.ysl2
@@ -6,123 +6,14 @@ include yslt.yml2
 
 tstylesheet {
     include standardlib.ysl2
+    include idl_api.ysl2
 
-    // stdlib candidates
-    // -----------------
-    def "func:autocomma" {
-        result if "position()!=last()" > ,
-    }
-
-    def "func:exists" {
-        param "xpath";
-
-        choose {
-            when "$xpath"
-                result "true()";
-            otherwise
-                result "false()";
-        }
-    }
-
-    // idl-api (ysl2)
-    // --------------
-    def "func:idl_typekind_is_defined" {
-        param "typekind";
-        result "func:exists(/pEpACIDLang/idl/typekinds//*[name()=$typekind])"
-    }
-
-    def "func:idl_typekind_is_generic" {
-        param "typekind";
-        result "func:exists(/pEpACIDLang/idl/typekinds/generics/*[name()=$typekind])"
-    }
-
-    def "func:idl_type_is_of_typekind_basetype" {
-        param "idltype";
-        result "func:exists(/pEpACIDLang/idl/basetypes/*[name()=$idltype])";
-    }
-
-    def "func:idl_type_is_of_typekind_deftype" {
-        param "idltype";
-        result "func:exists(//deftype[@name=$idltype])";
-    }
-
-    def "func:idl_type_is_of_typekind_enum" {
-        param "idltype";
-        result "func:exists(//enum[@name=$idltype])";
-    }
-
-    def "func:idl_type_is_of_typekind_struct" {
-        param "idltype";
-        result "func:exists(//struct[@name=$idltype])";
-    }
-
-    def "func:idl_type_is_of_typekind_list" {
-        param "idltype";
-        result "false()";
-    }
-
-    def "func:idl_type_is_defined" {
-        param "idltype";
-        choose {
-            when "func:idl_type_get_typekind_of_type($idltype)"
-                result "true()";
-            otherwise
-                result "false()";
-        }
-    }
-
-    def "func:idl_type_get_typekind_of_type" {
-        param "idltype";
-        choose {
-            when "func:idl_type_is_of_typekind_basetype($idltype)"
-                result > basetype
-            when "func:idl_type_is_of_typekind_deftype($idltype)"
-                result > deftype
-            when "func:idl_type_is_of_typekind_enum($idltype)"
-                result > enum
-            when "func:idl_type_is_of_typekind_struct($idltype)"
-                result > struct
-            when "func:idl_type_is_of_typekind_list($idltype)"
-                result > list
-            otherwise
-                result "false()";
-        }
-    }
-
-    def "func:idl_type_get_resolved_typekind" {
-        param "idltype";
-        const "idltypekind", "func:idl_type_get_typekind_of_type($idltype)";
-
-        choose {
-            when "$idltypekind = 'deftype'"
-                result "func:idl_type_get_typekind_of_type(func:idl_type_get_type_of_deftype($idltype))";
-            otherwise
-                result "$idltypekind";
-        }
-    }
 
-    def "func:idl_type_get_resolved_type" {
-        param "idltype";
-        const "idltypekind", "func:idl_type_get_typekind_of_type($idltype)";
-
-        choose {
-            when "$idltypekind = 'deftype'"
-                result "func:idl_type_get_type_of_deftype($idltype)";
-            otherwise
-                result "$idltype";
-        }
-    }
 
-    def "func:idl_type_get_type_of_deftype" {
-        param "idltype";
-        choose {
-            when "func:idl_type_is_of_typekind_deftype($idltype)"
-                result "//deftype[@name=$idltype]/as/@type";
-            otherwise
-                error > idl_resolve_deftype - is not a deftype: «$idltype»;
-        }
-    }
 
+    // ----------------------------------------------------------------------
+    // IG-C99
+    // ----------------------------------------------------------------------
 
     // typeclass is either
     // * primitive