The ifxptex package --- Detect pTeX and its derivatives

CTAN Homepage: https://ctan.org/pkg/ifxptex

Repository: https://github.com/Man-Ting-Fang/ifxptex

Version: 2017-12-27 v0.2

Copyright 2017 Yue ZHANG

License: Knuth License (https://ctan.org/license/knuth)

This package provides commands for detecting pTeX and its derivatives (e-pTeX,
upTeX, e-upTeX, and ApTeX). Both LaTeX and plain TeX are supported.