Possible compatibility problems with earlier versions marked with '*'.
+--- 1.0pl3 1996/1/2
+
+Various changes to retrieval module.
+
+Changed the union discriminators of the protocol files from enums to
+ints paired with #defines.
+
+*Changed oident.class to oident.oclass to avoid a reserved word in C++
+ compilers.
+
+*Changed operator in the RPN structure to 'roperator', again to avoid a
+ conflict with C++.
+
+Fixed problems in Explain decoders/encoders.
+
--- 1.0pl2 1995/12/6
Memory bug in log module fixed.