4TH file extension - Forth source code file
What is 4th file? How to open 4th files?
File type specification:
The 4th file extension is associated with the Forth programming language. The .4th file stores source code written in Forth.
Forth is a stack-based, extensible language without type-checking. It is probably best known for its "reverse Polish" (postfix) arithmetic notation, familiar to users of Hewlett-Packard calculators.