The z85 encoding is similar to the Ascii85 encoding. They're both ways to encode binary data as strings, but with different limitations and strengths. Base64 is a more common way to encode strings, but z85 and Ascii85 use more characters and can thus be a little more efficient - but at the cost of including characters that might be dangerous to use in some contexts.

For example, Ascii85 includes the \ character, which is used for character escapes in many contexts.