diff --git a/boot/boot.js b/boot/boot.js
index ac5d490a5..371bbf605 100644
--- a/boot/boot.js
+++ b/boot/boot.js
@@ -1806,9 +1806,13 @@ $tw.loadWikiTiddlers = function(wikiPath,options) {
 	// Save the original tiddler file locations if requested
 	var config = wikiInfo.config || {};
 	if(config["retain-original-tiddler-path"]) {
-		var output = {};
+		var output = {}, relativePath;
 		for(var title in $tw.boot.files) {
-			output[title] = path.relative(resolvedWikiPath,$tw.boot.files[title].filepath);
+			relativePath = path.relative(resolvedWikiPath,$tw.boot.files[title].filepath);
+			output[title] =
+				path.sep === path.posix.sep ?
+				relativePath :
+				relativePath.split(path.sep).join(path.posix.sep);
 		}
 		$tw.wiki.addTiddler({title: "$:/config/OriginalTiddlerPaths", type: "application/json", text: JSON.stringify(output)});
 	}
diff --git a/editions/dev/tiddlers/system/ContributionBanner.tid b/editions/dev/tiddlers/system/ContributionBanner.tid
new file mode 100644
index 000000000..f9ec77791
--- /dev/null
+++ b/editions/dev/tiddlers/system/ContributionBanner.tid
@@ -0,0 +1,20 @@
+title: $:/ContributionBanner
+tags: $:/tags/EditTemplate
+list-after: $:/core/ui/EditTemplate/title
+
+\define makeGitHubLink()
+https://github.com/Jermolene/TiddlyWiki5/edit/master/editions/dev/tiddlers/$(githubLink)$
+\end
+\define innerMakeGitHubLink(linkText)
+<$set name="githubLink" value={{$:/config/OriginalTiddlerPaths##$(draftOfTiddler)$}}>
+<a href=<<makeGitHubLink>> class="tc-tiddlylink-external" target="_blank" rel="noopener noreferrer">$linkText$</a>
+</$set>
+\end
+\define outerMakeGitHubLink(linkText)
+<$set name="draftOfTiddler" value={{$(currentTiddler)$!!draft.of}}>
+<<innerMakeGitHubLink "$linkText$">>
+</$set>
+\end
+<div class="tc-improvement-banner">
+{{$:/core/images/star-filled}} Can you help us improve this documentation? [ext[Find out how|https://tiddlywiki.com/#Improving%20TiddlyWiki%20Documentation]] to edit <<outerMakeGitHubLink "this tiddler on ~GitHub">>
+</div>
diff --git a/editions/dev/tiddlers/system/Sources.tid b/editions/dev/tiddlers/system/Sources.tid
new file mode 100644
index 000000000..0c5082205
--- /dev/null
+++ b/editions/dev/tiddlers/system/Sources.tid
@@ -0,0 +1,23 @@
+title: $:/editions/tw5.com/TiddlerInfo/Sources
+tags: $:/tags/TiddlerInfo
+caption: Sources
+
+\define github-link-base()
+https://github.com/Jermolene/TiddlyWiki5/blob/master/editions/dev/tiddlers/$(title)$
+\end
+
+\define make-github-link()
+<$set name="title" value={{$:/config/OriginalTiddlerPaths##$(currentTiddler)$}}>
+<$set name="title" filter="[<title>encodeuricomponent[]]" select="0">
+<a href=<<github-link-base>> class="tc-tiddlylink-external" target="_blank" rel="noopener noreferrer"><$text text=<<github-link-base>>/></a>
+</$set>
+</$set>
+\end
+
+<$list filter="[all[current]!is[system]!is[shadow]]">
+
+Help us to improve the documentation by sending a ~GitHub pull request for this tiddler:
+
+* <<make-github-link>>
+
+</$list>
diff --git a/editions/dev/tiddlywiki.info b/editions/dev/tiddlywiki.info
index e5bdacf77..572c5782b 100644
--- a/editions/dev/tiddlywiki.info
+++ b/editions/dev/tiddlywiki.info
@@ -56,5 +56,8 @@
 			"--rendertiddler","$:/core/templates/alltiddlers.template.html","alltiddlers.html","text/plain",
 			"--rendertiddlers","[!is[system]]","$:/core/templates/static.tiddler.html","static","text/plain",
 			"--rendertiddler","$:/core/templates/static.template.css","static/static.css","text/plain"]
+	},
+	"config": {
+		"retain-original-tiddler-path": true
 	}
 }
diff --git a/editions/tw5.com/tiddlers/filters/syntax/Filter Expression.tid b/editions/tw5.com/tiddlers/filters/syntax/Filter Expression.tid
index 694f44dc2..430a900cd 100644
--- a/editions/tw5.com/tiddlers/filters/syntax/Filter Expression.tid	
+++ b/editions/tw5.com/tiddlers/filters/syntax/Filter Expression.tid	
@@ -1,5 +1,5 @@
 created: 20150124182421000
-modified: 20150124184900000
+modified: 20171212073225103
 tags: [[Filter Syntax]]
 title: Filter Expression
 type: text/vnd.tiddlywiki
@@ -14,15 +14,35 @@ type: text/vnd.tiddlywiki
 
 A <<.def "filter expression">> is the outermost level of the [[filter syntax|Filter Syntax]]. It consists of one or more [[runs|Filter Run]].
 
-A run's input is normally a list of all the non-[[shadow|ShadowTiddlers]] tiddler titles in the wiki (in no particular order). But the `+` prefix can change this.
+If a run has:
 
-* If a run has no `+` or `-` prefix, its output titles are [[dominantly appended|Dominant Append]] to the filter's output.
-* If a run has a `-` prefix, its output titles are <<.em removed>> from the filter's output (if they were present).
-* If a run has a `+` prefix, it receives the filter's output so far as its input. The filter's output is then completely <<.em replaced>> by the run's output. Any subsequent run reverts to receiving all tiddler titles as its input, unless it too has a `+` prefix.
+* no prefix, its output titles are [[dominantly appended|Dominant Append]] to the filter's output
+* the prefix `-`, output titles are <<.em removed>> from the filter's output (if such tiddlers exist)
+* the prefix `+`, it receives the filter output so far as its input; its output then <<.em "replaces">> all filter ouput so far and forms the input for the next run
 
-In concise technical terms:
+In technical / logical terms:
 
 |!Run |!Interpretation |!Output |
 |`run` |union of sets |... OR run |
 |`+run` |intersection of sets |... AND run |
 |`-run` |difference of sets |... AND NOT run |
+
+A run's input is normally a list of all the non-[[shadow|ShadowTiddlers]] tiddler titles in the wiki (in no particular order). But the `+` prefix can change this:
+
+|Prefix|Input|h
+|`-` or none| <$link to="all Operator">`[all[]]`</$link> tiddler titles, unless otherwise determined by the first [[filter operator|Filter Operators]]|
+|`+`|the filter output of all previous runs so far|
+
+Precisely because of varying inputs, be aware that both prefixes `-` and `+` do not behave inverse to one another!
+
+For example, in both of the following, `$:/baz` will only be removed if it actually exists:
+
+* <$link to="is Operator"> `foo bar $:/baz -[is[system]]`</$link>
+* <$link to="prefix Operator">`foo bar $:/baz -[prefix[$:/]]`</$link>
+
+To understand why, consider the input for both final runs with their `-` prefix.
+
+In order to remove `$:/baz` in any case, existing or not, simply use the `+` prefix with [[negated filter operators|Filter Operators]]:
+
+* <$link to="is Operator">`foo bar $:/baz +[!is[system]]`</$link>
+* <$link to="prefix Operator">`foo bar $:/baz +[!prefix[$:/]]`</$link>