Another comment on MSC: while I'm happy that this classification of mathematical content exists, it seems to me that in graph theory it is not sufficiently deep (and also misses some topics). That's the reason why we chose to create a different subject tree. And partially it's also the reason why we hesitate to create new categories in areas outside our field of expertize: we would like to have a classification scheme that makes sense to people working in any particular area: and we can't easily judge this. Also, some fields may be more active than others (or have more problems that are easy to explain), and this should possibly be also taken into account.
However, if you (or anyone) has a concrete suggestion, we welcome any ideas.
Re: MSC
Another comment on MSC: while I'm happy that this classification of mathematical content exists, it seems to me that in graph theory it is not sufficiently deep (and also misses some topics). That's the reason why we chose to create a different subject tree. And partially it's also the reason why we hesitate to create new categories in areas outside our field of expertize: we would like to have a classification scheme that makes sense to people working in any particular area: and we can't easily judge this. Also, some fields may be more active than others (or have more problems that are easy to explain), and this should possibly be also taken into account.
However, if you (or anyone) has a concrete suggestion, we welcome any ideas.