IPF (OS/2)

IPF is the raw source markup for INF, CHM, and HLP files used in OS/2 and Dos-based Windows. The format uses a variation of HTML, which is then “compiled” into an indexed self contained web site that can be read offline. The format is an early form of e-book.

Concerns
The markup document itself can be compiled by any version of the supporting application. However, the Help format output changes slightly between Windows and OS/2. Further, each version of the used operating system includes minor changes to the Help Viewer and Info. General compatibility appears consistent though minor errors may occur when using an HLP, INF, or CHM file of another operating system version. Backwards compatibility is often complete, however forward compatibility, using a newer file on an older version, will often result in garbage text appearing where tags are unknown.