BASIC Instr() runtime error

[fpy]

From InStr Function

To avoid a run-time error, do not set the Compare parameter if the first optional parameter is omitted.

this could make sense with positional parameters,
but why does it get a runtime error on

Instr(String1:="Office Calc", String2:="C", Compare:=0) '  

also, why is Start declared as String in stdobj.cxx (revision 98f88ac1) - OpenGrok cross reference for /core/basic/source/runtime/stdobj.cxx ?

[sokol92]

By the way, in VBA this function (InStr) cannot be called in the notation with named parameters.
So the developers have already moved forward compared to VBA.