Files with hph file extension can be found as part of old Designer Graphics System 2 software.
HPH file extension - Designer Graphics System 2 data
What is hph file? How to open hph files?
File type specification:
The hph file extension was apparently used for one of the default files in Designer Graphics System 2 program.
No further information could be found, so it is likely an obsolete product.
This hph file type entry was marked as obsolete and no longer supported file format.
This type of file is no longer actively used and is most likely obsolete. This is typically the case for system files in old operating systems, file types from long discontinued software, or previous versions of certain file types (like documents, projects etc.) that were replaced in higher versions of their original programs.