This is a BASE85 Encoding Visual Basic class that expands the text to be encoded by 4:5 i.e. uses 5 ASCII characters to represent 4 bytes with 80% accuracy. Used in Postscript and PDF documents. Useful if binary data needs to be persisted in ASCII text.

Currently it’s main uses are in Adobe PDF and PostScript file formats. It is also used by git to produce path of binary files i.e. used to encode the patch files. Here is their C implementation of Base85 encoding source code. This code extensively uses Modulus Operator to do the calculations. You can find more details on Modulus operator and some sample usage in this article.