# Where are special system words like MISSING listed (and what they do)?

**URL:** https://community.mp3tag.de/t/where-are-special-system-words-like-missing-listed-and-what-they-do/61331
**Category:** Support
**Created:** [June 22, 2023, 5:11am UTC](https://community.mp3tag.de/t/where-are-special-system-words-like-missing-listed-and-what-they-do/61331 "2023-06-22T05:11:14Z")
**Posts on this page:** 1
**Showing post:** 4

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### Author: ![ohrenkino](https://community.mp3tag.de/user_avatar/community.mp3tag.de/ohrenkino/32/4843_2.png) [@ohrenkino](https://community.mp3tag.de/u/ohrenkino)
#### Post date: [June 22, 2023, 10:37am UTC](https://community.mp3tag.de/t/where-are-special-system-words-like-missing-listed-and-what-they-do/61331/4 "2023-06-22T10:37:44Z")

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> [@dec](#):
>
> i mean, under 'FILTERS'????

Yes, just as has been revealed to you in your own thread:

> [@Logical Operators ... Blank etc](https://community.mp3tag.de/t/logical-operators-blank-etc/60843):
>
> i can't find any operators for things like ifblank, ifchar, ifnumeric, and such so, for example, how do i test for a blank tag field? this is obviously a very useful/important test

And these keywords only work in filters not application-wide.

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