.\" authorization. *
.\"***************************************************************************
.\"
-.\" $Id: tabs.1,v 1.25 2019/06/15 23:08:12 tom Exp $
+.\" $Id: tabs.1,v 1.26 2019/06/23 21:01:12 tom Exp $
.TH @TABS@ 1 ""
.ds n 5
.ie \n(.g .ds `` \(lq
The \fB\-d\fP (debug) and \fB\-n\fP (no-op) options are extensions not provided
by other implementations.
.PP
-A \fBtabs\fP utility appeared in PWB/Unix 1.0 (1977),
-and thereafter in 3BSD (1979).
-It supported a single \*(``\-n\*('' option
+A \fBtabs\fP utility appeared in PWB/Unix 1.0 (1977).
+There was a reduced version of the \fBtabs\fP utility
+in Unix 7th edition and in 3BSD (1979).
+The latter supported a single \*(``\-n\*('' option
(to cause the first tab stop to be set on the left margin).
That option is not documented by POSIX.
-Initially, \fBtabs\fP used built-in tables rather than the terminal database,
+.PP
+The PWB/Unix \fBtabs\fP utility, which was included in System III (1980),
+used built-in tables rather than the terminal database,
to support a half-dozen terminal types.
It also had built-in logic to support the left-margin,
as well as a feature for copying the tab settings from a file.
.PP
POSIX documents no limits on the number of tab stops.
Documentation for other implementations states that there is a limit on the
-number of tab stops.
+number of tab stops
+(e.g., 20 in PWB/Unix's \fBtabs\fP utility).
While some terminals may not accept an arbitrary number
of tab stops, this implementation will attempt to set tab stops up to the
right margin of the screen, if the given list happens to be that long.