The keywords are tokenized, the line number is converted to a 16bit integer, leading spaces are stripped (which is why some "formatted" BASIC uses ":" as the first character in a line, like the following), everything else is kept intact.

10 for i = 1 to 10

20 : (arbitrary number of spaces) print "hello"

30 next

The short hand issue is real, too:

1?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?:?

expands into six lines of "1 print:print:....:print" that you can't simply edit because the limit is 80 characters (two lines)