# DP: document deprecated syntax for arithmetic evaluation.

--- a/doc/bash.1
+++ b/doc/bash.1
@@ -4190,6 +4190,9 @@ The format for arithmetic expansion is:
 \fB$((\fP\fIexpression\fP\fB))\fP
 .RE
 .PP
+The old format \fB$[\fP\fIexpression\fP\fB]\fP is deprecated and will
+be removed in upcoming versions of bash.
+.PP
 The
 .I expression
 undergoes the same expansions