If you are encountering this term while attempting to update a system or a specific piece of hardware:
: General addenda are being phased out. Comments must now be placed directly within the relevant section of the form (e.g., specific notes on foundation repairs must stay in the "Foundation" section). 101mrar upd
The "upd" likely refers to recent (such as UAD 3.6), which are modernizing these forms to replace free-form text with standardized data. Guide to the 101-MRAR Appraisal Update If you are encountering this term while attempting
Recent updates aim to eliminate ambiguity in appraisal reports: Guide to the 101-MRAR Appraisal Update Recent updates
Modern 101mrar upd files are likely using the format, which has a different header structure than legacy RAR. Ensure your tools support it. WinRAR 5.0+ does; older versions of 7-Zip may fail.
Certain industrial control systems and legacy hardware distribute firmware updates as split RAR volumes. The 101mrar upd might be the third or fourth part of a firmware update that corrects a specific memory addressing issue (Error Code 101).