In said:
IMO there is no such thing.
10 PRINT "Hello world"
20 END
The K'n'K specification was a fairly good guide for writing portable
BASIC programs, as practically all the BASIC implementors took it as
the starting point for defining their own dialects. Except for some
mini-BASICs that replaced floating point arithmetic by integer arithmetic,
to be able to fit inside 4K of ROM.
An interesting case is Sinclair BASIC (for the early Sinclair machines,
including the original Spectrum). It wouldn't accept something like
"I = 10", but there was no way to type such an instruction using the
integrated BASIC editor: you could only type "LET I = 10", because the
first key pressed when typing an instruction (ignoring the line number)
was interpreted as a BASIC keyword (the editor was in "keyword mode" at
that point and the K cursor was displayed on the screen).
Dan