Gotchas by using tagnavi_custom.config to List by Comment Field

[Alan P-Ten]

Sansa Clip Zip with firmware 01.01.21, Rockbox 3.13

First, I'm a newbie and NOT a programmer.  I've created a .rockbox/tagnavi_custom.config file to list titles by comment field (ID3v2.3 COMM) in order to list titles by mood. I would have preferred using the Other tag (ID3v2.3 TXXX) or mood tag (ID3v2.4 TMOO), but alas neither are support in Rockbox.

It does seem to work through trial and error. (Lot's of error  as I still not understand the syntax.) 

I'm doing this as an alternative to playlist. My questions are:
1. What gotchas do you see (if any) of doing this?
2. Any alternative to the comment field?
3. And of course, I will always appreciate an explanation of what this code means or any suggested improvements.

Thanks.

Code follows:
===========

#! rockbox/tagbrowser/2.0
# My custom database to define mood!

# Basic format declarations
#      I have know idea what goes here if anything!

%menu_start "custom" "Choose Mood..."
"Fast"        -> title ? comment = "fast"    -> title = "fmt_title"
"Slow"        -> title ? comment = "slow"    -> title = "fmt_title"
"Cheery"      -> title ? comment = "cheery"    -> title = "fmt_title"
"Uplifting"   -> title ? comment = "uplifting"    -> title = "fmt_title"
"Romantic"    -> title ? comment = "romantic"    -> title = "fmt_title"
"Untagged"    -> title ? comment = "<untagged>"    -> title = "fmt_title"

# Fast = Rowdy, rhythmic, passionate, rousing, boisterous, aggressive, fiery
# Slow = Melodic, poignant, wistful, autumnal, brooding, bittersweet
# Cheery = Rollicking, fun, sweet, humorous, silly, campy, quirky, whimsical
# Uplifting = inspirational, spiritual
# Romantic = Sexy, erotic, amorous, passionate, tender, affectionate

# ^ An empty line ends the menu