For example in Xorg.0.log ...
[ 15708.908] (WW)
And in the log files it states
[ 15708.905] Markers: (--) probed, (**) from config file, (==) default setting,
(++) from command line, (!!) notice, (II) informational,
(WW) warning, (EE) error, (NI) not implemented, (??) unknown.`
Is the first number the time?
Is there any literature on this subject? Or suggested ways to read through them and be able to make sense of them more fully?
There are essentially no standard formats for log files. They are a "dumping ground" of sorts filled with information the authors of the software deem interesting or useful.
Often there are mechanisms to control the verbosity of the logging in the configuration files for the software. This can be useful when troubleshooting as it gives usually much more information which may lead to a solution. Once things are working the way they should be, the log level can be adjusted to only show errors or extreme situation for example.
Virtually all software that performs logging does this in different ways in my experience.
I would guess that the first field in that example is the timestamp of the logged event represented as seconds since boot.