# Preventing empty output lines in export **URL:** \ **Category:** Support\ **Created:** [March 13, 2016, 9:27pm UTC](https://community.mp3tag.de/t/preventing-empty-output-lines-in-export/17746 "2016-03-13T21:27:45Z")\ **Posts on this page:** 1\ **Showing post:** 2
**Author:** ![DetlevD](https://community.mp3tag.de/user_avatar/community.mp3tag.de/detlevd/32/123_2.png) [@DetlevD](https://community.mp3tag.de/u/DetlevD)\ **Post date:** [March 14, 2016, 8:12am UTC](https://community.mp3tag.de/t/preventing-empty-output-lines-in-export/17746/2 "2016-03-14T08:12:32Z")
> [@just\_Addict](#): > > I've defined an mte export and read in the online help and also observed this in action that if you enclose a tag frame variable within right-angled brackets '[' and ']', it will not generate blank output if there is no value for the given tag frame variable. ... > To my surprise the suppression of blank output then fails and outputs the line as if a value was present ... Yes, in Mp3tag scripting language the [...] square bracket clamp is an operator. Once there is any tagfield content operator within the square bracket clamp, e. g. %TITLE%, which owns a value, then the entire content of the square bracket clamp will be come into usage. This scripting line ... **[PERFORMER "$if(%ALBUMARTIST%,%ARTIST%,)"]** ... or written as ... **['PERFORMER "'$if(%ALBUMARTIST%,%ARTIST%,)'"']** ... has the meaning of ... "If ALBUMARTIST exists, then write ARTIST, else write nothing." If ALBUMARTIST does not exist, but ARTIST exist, then the result is the text: **'PERFORMER ""'** Probably you want this expression ... **['PERFORMER "'$if2(%ALBUMARTIST%,%ARTIST%)'"']** ... with the meaning of ... "If both tagfields do not exist, then the result is an empty string." DD.20160314.1042.CET --- _[View the full topic](https://community.mp3tag.de/t/preventing-empty-output-lines-in-export/17746)._