When you want to update or merge a file, use the update command. For files that are not up to date this is roughly equivalent to a checkout command: the newest revision of the file is extracted from the repository and put in your working directory.
Your modifications to a file are never lost when you use update. If no newer revision exists, running update has no effect. If you have edited the file, and a newer revision is available, cvsnt will merge all changes into your working copy.
For instance, imagine that you checked out revision 1.4 and started editing it. In the meantime someone else committed revision 1.5, and shortly after that revision 1.6. If you run update on the file now, cvsnt will incorporate all changes between revision 1.4 and 1.6 into your file.
If any of the changes between 1.4 and 1.6 were made too close to any of the changes you have made, an overlap occurs. In such cases a warning is printed, and the resulting file includes both versions of the lines that overlap, delimited by special markers. the section called “update--Bring work tree in sync with repository”, for a complete description of the update command.