document strength directive

diff --git a/doc/magic.man b/doc/magic.man
index e3dfd96eaf5f6a60befc162103ee7121725a3f7c..b624c73e6e57582f08524793f96a67025e530f48 100644 (file)
--- a/doc/magic.man
+++ b/doc/magic.man
@@ -1,5 +1,5 @@
-.\" $File: magic.man,v 1.55 2008/02/28 22:24:46 rrt Exp $
-.Dd January 10, 2007
+.\" $File: magic.man,v 1.56 2008/03/01 22:21:48 rrt Exp $
+.Dd August 30, 2008
 .Dt MAGIC __FSECTION__
 .Os
 .\" install as magic.4 on USG, magic.5 on V7, Berkeley and Linux systems.
@@ -301,6 +301,26 @@ i.e. the literal string
 .Dq !:mime
 followed by the MIME type.
 .Pp
+An optional strength can be supplied on a separate line which refers to
+the current magic description using the following format:
+.Bd -literal -offset indent 
+!:strength OP VALUE
+.Ed
+.Pp
+The operand
+.Dv OP
+can be: 
+.Dv + ,
+.Dv - ,
+.Dv * ,
+or
+.Dv /
+and
+.Dv VALUE
+is a constant between 0 and 255.
+This constant is applied using the specified operand
+to the currently computed default magic strength.
+.Pp
 Some file formats contain additional information which is to be printed
 along with the file type or need additional tests to determine the true
 file type.