With php 4.4 and 5.1 phpPeanuts still triggers some notifications "Only variable references should be returned by reference": When a function that returns a PntError it is not first put into a variable.
Reference Anomalies: Before the generic workaround was applied (introduced in 1.1 beta 1, released dd 16-11-2004), use of references by phpPeanuts occasionally made uninitialized php variables or associations arbitrarily hold values that seemed to come from another variable. This rarily happened and since the generic workaround it did not happen again until the changes where made to get rid of reference notifications. Read the "remarks for use with existing applications" in the release notes to avoid them. Do not use phpPeanuts for mission critical applications.
produces E_STRICT notifications on php5 (see release notes under portability).