* src/bin/man/ltlcross.x: Document %N, %T, %H.

src/bin/man/ltlcross.x

@@ -200,6 +200,44 @@ of course used the result of each translator.  When the
 \fB\-\-products\fR=\fIN\fR option is used, these values are averaged
 over the \fIN\fR products performed.
 
+[DEPRECATED OUTPUT SPECIFIERS]
+Until version 1.2.6, the output of translators was specifed using the
+following escape sequences.
+.PP
+.TP
+%N
+An output file containing a never claim.
+.TP
+%T
+An output file in \fBlbtt\fR's format.
+.TP
+%D
+An output file in \fBltl2dstar\fR's format.
+.PP
+Some development versions leading to 1.99.1 also featured
+.PP
+.TP
+%H
+An output file in the HOA format.
+.PP
+Different specifiers were needed because Spot implemented
+different parsers for these formats.  Nowadays, the parsers
+for never claims, lbtt's format, and HOA format have been merged into
+a single parser that is able to distinguish these three formats
+automatically.
+.B ltlcross
+officially supports only two output specifiers
+.TP
+%O
+An output file in either \fBlbtt\fR's format, as a never claim,
+or in the HOA format
+.TP
+%D
+An output file in \fBltl2dstar\fR's format.
+.P
+For backward compatibility, the sequences %N, %T, and %H are still
+supported (as aliases for %O), but are deprecated.
+
 [SEE ALSO]
 .BR randltl (1),
 .BR genltl (1),