Tag 109 does not display Field Name value

[techie2000]

Expected Output

119 | ClientID | BLAH

Actual Output

109 |   | BLAH

[whatthefrog]

you are right, it is missing in the data.js

https://github.com/drewnoakes/fix-decoder/blob/master/src/scripts/app/data.js#L836

https://www.onixs.biz/fix-dictionary/4.4/tagnum_109.html
might be because

No longer used as of FIX 4.3. Included here for reference to prior versions.

I would recommend to hint this fact when adding it to the definition, e.g. "ClientID (<=4.2)"