File extension R13 is associated with RAR compressed files from a multi-volume archive.File extension r13 is a part file from a multi-volume compressed RAR archive (you need all files together (e.g. rar, r01, r02, r03, r04, r05 etc. to decompres archive contents). RAR is the native format of WinRAR archiver. Like other archives, RAR files are data containers, they store one or several files in the compressed form. After you downloaded RAR file from Internet, you need to unpack its contents in order to use it. Some RAR files can be parts of multi-volume sequences. In WinRAR you can split a huge archive to a few smaller files, which are called volumes. They may have extensions .rar (the first volume), .r00, .r01, .r02 ..., or .part1.rar (the first volume), .part2.rar, .part3.rar ..., or .001, 002, 003, ... etc. If you need to unpack volumes, place all them to the same folder and start extraction from the first volume.
File extension R13 is associated with Norton Ghost rar file. File extension is used by Norton Ghost. Backup file in RAR compression format. .r13 file extension is most often used by WinRAR for split archive file.
File extension r13 can be opened by 3rd PlanIt .