Difference between Full BASIC and Microsoft BASIC

END-statement

On Microsoft BASIC, END means finishing the program, but on ISO Full BASIC, END means that line is the final line of the main program.
Only external SUBs, external function definitions, external picture definitions, and modules are written followed by the END line.
Any subroutine invoked by a GOSUB statement is not put below the END-line.
DATA statements that supplies for READ statements in the mainprogram must be written in the mainprogram.

How to write DATA statements
DATA statements can be written anywhere above the END-line.

How to write a subroutine