I am struck by the, let's say, lexical heterogeneity of the entries in the `geneSymbol` column of UCSC hg19's `kgXref` table. Here's a sample:
Ig alpha 1-[alpha]2m
aromatase cytochrome P-450 (P-450AROM)
immunoglobulin epsilon chain constant...
T-cell receptor alpha chain variable ...
I would like to know more about the "semantics" of this table's `geneSymbol` column, but I am having a really hard time finding authoritative answers to my questions. (These questions include, among others, the following. What is the provenance of these "gene symbols"? Is UCSC the ultimate authority on them, or are they getting these symbols from some other authority? Who/what ensures that distinct symbols always refer to distinct genes? Etc.)
If I go to
select `kgXref` from the "table" dropdown, and then click on "describe table schema", the resulting page shows a lot of useful information, but it does not tell me anything about how this table was put together. In particular, it tells me nothing relevant to questions like the ones mentioned earlier.
 The `...` at the end of the last two entries in the list belong, in fact, to the values stored in the table. The length of both of these `geneSymbol` entries is 40; they are the longest ones in the table. FWIW, the type of the `geneSymbol` column is `varchar(255)`.
 By "authoritative answers" I mean answers that come from a publication (preferably peer-reviewed) authored by those who produced the database. It is not too difficult to come by educated guesses to answer at least some of these questions. I probably could do a passable job myself, but this is not what I am after.