diff --git a/core/modules/filters/is/blank.js b/core/modules/filters/is/blank.js
new file mode 100644
index 000000000..8f500da45
--- /dev/null
+++ b/core/modules/filters/is/blank.js
@@ -0,0 +1,36 @@
+/*\
+title: $:/core/modules/filters/is/blank.js
+type: application/javascript
+module-type: isfilteroperator
+
+Filter function for [is[blank]]
+
+\*/
+(function(){
+
+/*jslint node: true, browser: true */
+/*global $tw: false */
+"use strict";
+
+/*
+Export our filter function
+*/
+exports.blank = function(source,prefix,options) {
+	var results = [];
+	if(prefix === "!") {
+		source(function(tiddler,title) {
+			if(title) {
+				results.push(title);
+			}
+		});
+	} else {
+		source(function(tiddler,title) {
+			if(!title) {
+				results.push(title);
+			}
+		});
+	}
+	return results;
+};
+
+})();
diff --git a/editions/tw5.com/tiddlers/filters/is.tid b/editions/tw5.com/tiddlers/filters/is.tid
index 6e838e872..bec256edf 100644
--- a/editions/tw5.com/tiddlers/filters/is.tid
+++ b/editions/tw5.com/tiddlers/filters/is.tid
@@ -13,7 +13,7 @@ op-neg-output: those input tiddlers that do <<.em not>> belong to category <<.pl
 
 The parameter <<.place C>> is one of the following fundamental categories:
 
-|!Category |!Matches any tiddler that... |
+|!Category |!Matches any tiddler title that... |
 |^`current` |is the [[current tiddler|Current Tiddler]] |
 |^`image` |has an image ContentType |
 |^`missing` |does not exist (other than possibly as a shadow tiddler), regardless of whether there are any links to it |
@@ -22,7 +22,8 @@ The parameter <<.place C>> is one of the following fundamental categories:
 |^`system` |is a [[system tiddler|SystemTiddlers]], i.e. its title starts with `$:/` |
 |^`tag` |is in use as a tag |
 |^`tiddler` |exists as a non-shadow tiddler |
-|^`variable` |<<.from-version "5.1.20">> exists as a variable (whether or not it has a non-blank value) |
+|^`variable` |<<.from-version "5.1.20">> exists as a variable (whether or not that variable has a non-blank value) |
+|^`blank` |<<.from-version "5.1.20">> is blank (i.e. is a zero length string) |
 
 If <<.place C>> is anything else an error message is returned. <<.from-version "5.1.14">> if <<.place C>> is blank, the output is passed through unchanged (in earlier versions an error message was returned).