[tz] [PROPOSED 3/5] Document zic abbreviation rules

[Paul Eggert]

* NEWS, zic.8: Describe how zic supports abbreviations like "Sun".
---
 NEWS  |  3 +++
 zic.8 | 11 +++++++++--
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/NEWS b/NEWS
index dcd49eb..1af7b69 100644
--- a/NEWS
+++ b/NEWS
@@ -28,6 +28,9 @@ Unreleased, experimental changes
     bit easier to port to MS-Windows.  (Thanks to Kees Dekker for
     reporting the problems.)
 
+  Changes to documentation and commentary
+
+    The zic man page now documents abbreviation rules.
 
 Release 2017b - 2017-03-17 07:30:38 -0700
 
diff --git a/zic.8 b/zic.8
index c59ccfc..6fee96d 100644
--- a/zic.8
+++ b/zic.8
@@ -148,7 +148,8 @@ Non-blank lines are expected to be of one of three types:
 rule lines, zone lines, and link lines.
 .PP
 Names (such as month names) must be in English and are case insensitive.
-Abbreviations, if used, must be unambiguous in context.
+A name can be abbreviated by omitting all but an initial prefix; any
+abbreviation must be unambiguous in context.
 .PP
 A rule line has the form
 .nf
@@ -221,7 +222,13 @@ Sun<=25	last Sunday on or before the 25th
 .fi
 .in -.5i
 .sp
-Names of days of the week may be abbreviated or spelled out in full.
+A weekday name (e.g.,
+.BR "Sunday" )
+or a weekday name preceded by
+.q "last"
+(e.g.,
+.BR "lastSunday" )
+may be abbreviated or spelled out in full.
 Note that there must be no spaces within the
 .B ON
 field.
-- 
2.9.4