This page needs more research, and is partially based on speculation.

This is a type that is used to reference Unity Object Layout|Objects]] in the Unity serialized data format¹⁾. It is likely that this is a type only on the native side.

This type can appear in error messages as well as when querying a SerializedProperty.type. ²⁾

• https://answers.unity.com/questions/1432447/what-is-this-error-message-broken-text-pptr-in-fil.html