The previous edition of this book, which appeared in 1999, described OCL version 1.1. This edition describes OCL version 2.0. This appendix lists the differences between both versions of the OCL standard.
In version 1.1, there was no syntax for declaring the context of an expression; there was only the convention to underline the classname (for invariants) or the operation name (for pre- and postconditions) to indicate the context. In version 2.0, the context declaration is formalized. A new syntax is provided using the keyword context, and several different keywords indicate how the expression should be interpreted, e.g., inv and derive.