As we know, it has been nearly 6 months since the full release of the reviews section, which included the advanced category nesting system among other things. Unfortunately, it has not really been possible to do a full re-categorisation of existing submissions. I suppose part, if not most, of the problem is the impossibility of community involvement - new categories can only be created by administrators. Opening this up to the community would make things way more messy.
Thus, here's what I suggest - you can use this thread to suggest a category nesting for a specific submission in the reviews section. You can find all submissions here. Keep in mind the guidelines:
- start with the arxiv category (e.g. gr-qc),
- then either the arxiv sub-category or another such an equivalent topic (e.g. quant-gr; quantum gravity),
- then narrow it down to some closely related theories or fields of study (e.g. cqg-var; Canonical QG and variants)
- then narrow it down to a single theory or field of study (e.g. lqg; Loop Quantum Gravity)
- then pin it down to a niche probem or property (e.g. lqg-bh-entropy; the problem of BH entropy in LQG)
Some submissions are partially categorised (e.g. cond-mat, hep-th/string-th), some are not categorised at all, and are still in Reviews I. A few are fully re-categorised, e.g. gr-qc/quant-gr/cqg-var/lqg/lqg-bh-entropy, hep-th/amplituhedron, and you can use them as model category nests.