WL_HOME?

patch 21984589 readme says:

- Navigate to the {MW_HOME}/utils/bsu directory.

- Execute bsu.sh -install -patch_download_dir={MW_HOME}/utils/bsu/cache_dir -patchlist={PATCH_ID} -prod_dir={MW_HOME}/{WL_HOME}

I'm not clear on what WL_HOME is and it is not listed here, clearly anyway:  http://docs.oracle.com/cd/E24628_01/install.121/e24089/appdx_directory_structure.htm#EMADV12155

Could be, but it seems like the table should list :

wlserver_10.3, logs, utils, modules

These directories contain Fusion Middleware files.