I was curious, so I looked this up. Maybe I'm misunderstanding it, but it seems this may be what Coasty had in mind?
Notes
WoW reads up to the first 1024 characters of each line only. Additional characters are ignored and do not cause an error.
The .toc files are read only when the client initially starts up. Any changes made to the .toc file will be ignored by a running client until the client is restarted (more specifically, content read from .toc files is not refreshed when you reload the user interface or log out / log in. Although some changes will be picked up if you log out to the character selection screen and back in).
Prefixing a line with one # will mark it as a comment, meaning that it will not be read. For example:
# This is a comment
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Reference:
http://wowpedia.org/The_TOC_Format#Notes