The original WEB system by Donald Knuth has the macros webmac.tex that produce DVI output only; for historic reasons, it will never be modified (apart from catastrophic errors). Han The Thanh has modified these macros in his pdfwebmac.tex for PDF output (only) with pdfTeX. Jonathan Kew's XeTeX has similar macros xewebmac.tex by Khaled Hosny that modify webmac.tex for PDF output; these macros can only be used with a specific TeX engine each. The present pwebmac package integrates these three WEB macro files similar to cwebmac.tex in Silvio Levy's and Don Knuth's CWEB system, so pwebmac.tex can be used with Plain TeX, pdfTeX, and XeTeX alike.

Its initial application is the production of PDF and HINT files for all major WEB programs for TeX and friends. For this purpose, the shell script makeall was whipped together; it provides various command line options and works around several quirks in the WEB sources.

WEB programmers who want to use pwebmac.tex instead of the default webmac.tex in their programs have to change the first line in the TeX file created by weave. From there, all depends on the TeX engine you use.