(See RepositoryConversion for existing conversion tools)

This describes the basic steps needed to do history conversion from arbitrary formats, as implemented in Mercurial's convert-repo script:

 * Group changes into changesets
   
   This step is difficult for systems that don't have atomic commits. See cvsps for an example of how this can be done with CVS. 

 * Associate a unique identifier with each changeset
 
 * Generate the revision graph by finding the parent changesets of each changeset

 * Generate a topologically sorted list of changesets such that parents precede their children

 * For each changeset:

   * Extract or generate a changeset description, user name, and date
   * Extract a copy of each file changed in the changeset
   * Use the Mercurial rawcommit interface to explicitly commit the changeset
   * Save a correspondence map between source changeset IDs and Mercurial changeset IDs so that the process can be
     interrupted and resumed

 * Convert tags

   * Generate a list of tags and their corresponding source changeset IDs
   * Use the correspondence map to convert tags to Mercurial IDs
   * Write a .hgtags file
   * Commit .hgtags file
----
Some conversions can be very difficult. It would be worth checking out ProblematicConversions to see how one such conversion was handled.
----
CategoryConversion