Add a new node to the abstract symtax tree, which will let us do datatype checking of FB variable declarations using the standard algorithm, and no special cases.
IEC 61131-3 Annex F Examples (informative)
This directory contains example code take from:
Annex F of Draft 2nd edition of the IEC 61131-3 standard (1998)
"PROGRAMMABLE CONTROLLERS - PROGRAMMING LANGUAGES"