Using "Then" will also make it easier to format the source properly. I'd suggest you should use only these two forms:
or
This way it's still qbasic compatible, which was probably the most common basic on the pc platform for many years (byside visual basic, which is something comletely diffrent) and therefore it's a kind of a convention.
if you want to write multiple commands on one line, I'd suggest to always use the ":" as a seperator, eg:
if a=0 then b=1
or
if a=0 then b=1 c=2 endif
This way it's still qbasic compatible, which was probably the most common basic on the pc platform for many years (byside visual basic, which is something comletely diffrent) and therefore it's a kind of a convention.
if you want to write multiple commands on one line, I'd suggest to always use the ":" as a seperator, eg:
if a=1 then : b=2 : else : b=0 : endif