# Testing mp3tag behaviour **URL:** \ **Category:** Support\ **Created:** [July 26, 2018, 7:12pm UTC](https://community.mp3tag.de/t/testing-mp3tag-behaviour/42469 "2018-07-26T19:12:14Z")\ **Posts on this page:** 1\ **Showing post:** 3
**Author:** ![sheepdisease](https://community.mp3tag.de/letter_avatar_proxy/v4/letter/s/d07c76/32.png) [@sheepdisease](https://community.mp3tag.de/u/sheepdisease)\ **Post date:** [July 27, 2018, 6:57am UTC](https://community.mp3tag.de/t/testing-mp3tag-behaviour/42469/3 "2018-07-27T06:57:24Z")
Thank you for your comprehensive reply. As you mentioned tags, I was interested to see the ones listed within mp3tag so looked through the data folder. I then saw what you mean, as the following are labelled 'fields': TITLE ARTIST ALBUM YEAR TRACK GENRE COMMENT \_DIRECTORY ALBUMARTIST COMPOSER DISCNUMBER I notice that \_FILENAME is missing from this list, doesn't that seem strange? Not missing in documentation though: > **[Tag Field Mappings – Mp3tag Documentation](https://docs.mp3tag.de/mapping/)** > > Overview of all available tag fields, their names in Mp3tag, and how they are mapped to the internal structures of the different tag formats. Mp3tag is the universal Tag Editor. ALBUM ALBUMSORT ALBUMARTIST ALBUMARTISTSORT ARTIST ARTISTSORT BPM COMMENT COMPILATION COMPOSER COMPOSERSORT CONDUCTOR CONTENTGROUP COPYRIGHT DISCNUMBER ENCODEDBY ENCODERSETTINGS ENCODINGTIME FILEOWNER FILETYPE GENRE GROUPING INITIALKEY INVOLVEDPEOPLE ISRC LANGUAGE LENGTH LYRICIST MEDIATYPE MIXARTIST MOOD MOVEMENTNAME MOVEMENT MOVEMENTTOTAL MUSICIANCREDITS NETRADIOOWNER NETRADIOSTATION ORIGALBUM ORIGARTIST ORIGFILENAME ORIGLYRICIST ORIGYEAR PODCAST PODCASTCATEGORY PODCASTDESC PODCASTID PODCASTKEYWORDS PODCASTURL POPULARIMETER PUBLISHER RATING MM RATING WMP RELEASETIME SETSUBTITLE SUBTITLE TAGGINGTIME TITLE TITLESORT TRACK UNSYNCEDLYRICS WWW WWWARTIST WWWAUDIOFILE WWWAUDIOSOURCE WWWCOMMERCIALINFO WWWCOPYRIGHT WWWPAYMENT WWWPUBLISHER WWWRADIOPAGE YEAR I had looked through the documentation and find it strange some things are undocumented like `_TAG` & `_ALL`. From reading other posts there is a danger that irrelevant tags will be affected by using these 'pseudo-fields' with undesirable results. Otherwise tags and functionality are documented here: > **[Scripting Functions – Mp3tag Documentation](https://docs.mp3tag.de/scripting/)** > > Documentation on Mp3tag's scripting functions. Mp3tag is the universal Tag Editor. > **[Rearrange Parts of File Names – Mp3tag Documentation](https://docs.mp3tag.de/converters/rearrange-filenames/)** > > Documentation on Filename to Filename, a converter to rearrange parts of file names. Mp3tag is the universal Tag Editor. Having identified the disadvantages of using 'pseudo-fields', it is frustrating that there is not more functionality for changing multiple specific tags at the same time. In one of my other posts this was explored but of limited success using guess values. For example, [I have a list of band names](https://community.mp3tag.de/t/using-tag-in-actions-combining-actions-for-different-tags/42419/43) that I want to force to uppercase, but at the moment this means reproducing the list for several fields, which means if adding or removing from the list, it becomes very onerous. It would be much better to have one action within an action group to tackle all these fields at once, such as ALBUMARTIST, ARTIST & ARTISTS. Even better, it would be able to cope with \_FILENAME & \_DIRECTORY to cover all the relevant fields. There do appear to be limitations to using guess values in this way, in part because this use of functionality is not documented and because I still have limited understanding of correct syntax. This means I could be wasting my time trying to make something work that others know wont in the first place or I can't make it work when someone else could because it has not been written correctly. Here is an example: Guess values: `$replace(%ALBUMARTIST% === %ARTIST% === %ARTISTS%,'^(abba|adda|absrdst|acdc|ac dc|akdong musician|bkpr|blk jks|bts|chllngr|chvrches|chll pll|dfrnt|diiv|dmc|dnce|drwn|dtcv|dwntwn|dvsn|dvsr|exo-k|grmln|haim|htrk|hxlt|inxs|jmsn|jpnsgrls|kaytranada|kda|kshmr|ladybaby|lany|lee hi|lndn drgs|lnzndrf|lvthn|mgmt|mika|mnek|mndrmnek|ms mr|mstrkrft|n sync|nsync|partynextdoor|pwr bttm|pza|rdgldgrn|rkcb|rlyr|rÜfÜs du sol|rvivr|ry x|sbtrkt|shxcxchcxsh|sophie|stnnng|strfkr|swmrs|tnght|tr/st|tts|tstr|walk the moon|wzrd|u2|u-kiss|unkle|wstrn|xtrmst|zayn)$',$upper(%ALBUMARTIST% === %ARTIST% === %ARTISTS%)` String: `%ALBUMARTIST% === %ARTIST% === %ARTISTS%` Is this written correctly? Can you see a way of making this work correctly with \_FILENAME and \_DIRECTORY given the limitations forced onto mp3tag by Windows? --- _[View the full topic](https://community.mp3tag.de/t/testing-mp3tag-behaviour/42469)._