The usage excerpt for tag coding-theory reads:
Use this tag for questions about source coding, error-correcting codes, error-detecting codes, and related algebraic and/or combinatoric constructions.
I think the use of the term "source coding" here is misleading. See for example How many "2-times" exist between two given digital times, where the OP clearly thinks this tag is relevant because he or she is interested in some theory to support a coding project. I am not sure what the best fix is. Perhaps change "source coding" to "source-coding and channel-coding in information theory", or just get rid of it altogether and leave the concepts of source- and channel-coding to the full description of the tag.
I am not familiar with the process for suggesting improvements to tags, so I didn't want just to dive in and change things. (Presumably suggested improvements do get reviewed?)