Document URL: 

https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/System_Administrators_Guide/chap-Managing_Services_with_systemd.html
Section Number and Name: 

Describe the issue: 

in table 8.2, "Systemd Unit Locations", the third entry describes the directory
/etc/systemd/system/ as:

"Systemd units created and managed by the system administrator. This
directory takes precedence over the directory with runtime units."

that note seems pretty clearly to imply that whatever shows up in that
directory is only there due to explicit action by the system
administrator, but that directory is already populated.

Suggestions for improvement:

Explain more accurately what the directory contains

Additional information: 

Thank you to Robert P.J. Day for reporting this matter.