[1003.1(2013)/Issue7+TC1 0000877]: tail should support the -r option

[Thomas E. Dickey]

UNIX systems include support for tail -r since at least 1980.

It would be nice to have a verifiable reference for this statement.

The POSIX standard should follow existing practice.

z/OS does not document this feature.
http://www-01.ibm.com/support/knowledgecenter/SSLTBW_2.1.0/com.ibm.zos.v2r1.bpxa500/tail.htm?lang=en

Additionally, it does not appear in this HPUX documentation:

http://docstore.mik.ua/manuals/hp-ux/en/B2355-60130/tail.1.html