def spec(self, insn, record):
         def merge(vector, value, span, spec, spec_span):
             bits = (len(span) + len(spec_span))
@@ -6,14 +6,14 @@
             spec = _SelectableInt(value=spec.value, bits=bits)
             # this is silly these should be in a general base class,
             # settable by constructor
-            vshift = 2
-            sshift = 5
-            spshft = 0
+            vshift = 4
+            sshift = 3
+            spshft = 2
             if vector:
                 value = ((value << vshift) | (spec<<spshft))
-                span = (span + spec_span)
+                span = (span[0:3] + spec_span + ('{0}', '{0}') + span[3:5])
             else:
                 value = ((spec << sshift) | value)
-                span = (spec_span + span)
+                span = (('{0}', '{0}') + spec_span + span)

             return (value, span)