A collection of changes to a repository is called a changeset. A changeset that has been placed in a repository is said to be committed. We can list changesets that have been committed. For example, if we would like to know what the last changeset that was committed to this part of the repository is, we would issue the following command:
$ svn log -r PREV:HEAD
The -r subversion switch allows us to specify revisions—numeric representations of each change. PREV and HEAD are special references, being the previous version and latest version, respectively. Sometimes, we might be instructed to test or use a specific version, called a revision. In that case, it is possible to retrieve it by issuing this command:
$ svn up ...
