Log record and Diff between two revisions of a file.

To see log history:
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* cvs log foo.java

To see different versions of diff:
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* cvs diff -r1.0 -r1.1 foo.java
* cvs diff -u -w -r1.21.2.6 foo.java - This is more meaningful.
* cvs diff -c -w -r1.4 foo.java