This library reference documents the library set V2.1.3.
This is the library set which is recommended for use with all new projects.
Here is the breakdown of available libraries, by levels. The levels reflect library dependencies. For example, the SOCK and FILENUM libraries are on the lowest level because they do depend on any other libraries. The STG (settings) library is one level higher because its operation requires the services of the FILENUM library (albeit optionally).
Dependencies may be "hard", soft, or conditional. Hard dependency is when "library A relies on library B". For example, the DHCP library needs the SOCK library, or the project won't even compile.
Soft dependencies are caused by the anticipated logic of operation. For example, the DHCP library does not technically need the STG library. However, as demonstrated in the DHCP sample code, it is nice to have the STG library in the project because it can help us store the obtained IP. Hence, the DHCP library sits higher than the STG library.
Example of a conditional dependency: the DHCP library doesn't require the WLN library, unless you want to run DHCP over the Wi-Fi interface, in which case the WLN library becomes necessary.
STG (Settings); TBL (Tables) [not yet documented]
The Library Reference section introduces libraries in the top-to-bottom order.