diff --git a/ppd/PPD.pm b/ppd/PPD.pm
index 986b41c73e707f5664228dbd2447a94fdc131315..4b485c6398b0ff150ff366dcdc1bd792ca6ebca5 100644
--- a/ppd/PPD.pm
+++ b/ppd/PPD.pm
@@ -38,6 +38,8 @@ our @EXPORT = qw(define_group define_ui_group switch_group declare get set maybe
 #	Default => key,		# default value if not marked inside Values
 #	Custom => [		# further values with custom parameters (mostly a CUPS extension)
 #		PS => string,		# PS code invocation to emit (with parameters on the stack)
+#					# For JCL options, a JCL command is given with "\1" etc.
+#					# as placeholders for the actual values.
 #		Params => [		# list of parameters (mandatory)
 #			{ Key => key,		# key (mandatory)
 #			  Name => name,		# descriptive name (default: same as Key)