diff --git a/doc/todo/osm_plugin_GeoJSON_popup_patch.mdwn b/doc/todo/osm_plugin_GeoJSON_popup_patch.mdwn
index 8b0996fe0..117aefc51 100644
--- a/doc/todo/osm_plugin_GeoJSON_popup_patch.mdwn
+++ b/doc/todo/osm_plugin_GeoJSON_popup_patch.mdwn
@@ -3,4 +3,71 @@
 
 When using the GeoJSON output of the OSM plugin (osm_format: GeoJSON), the name and description in the popups are missing, this patch fixes the issue.
 
-
+> "Pass the layers given in the OSM directive through"
+>
+> It would be good if the commit added documentation for the new feature,
+> probably in `doc/ikiwiki/directive/osm.mdwn`.
+>
+>     +	my @layers = [ 'OSM' ];
+>
+> You mean `$layers`. `[]` is a scalar value (a reference to an array);
+> `@something` is an array.
+>
+>     +		@layers = [ split(/,/, $params{layers}) ];
+>
+> Is comma-separated the best fit here? Would whitespace, or whitespace and/or
+> commas, work better?
+>
+> It's difficult to compare without knowing what the values would look like.
+> What would be valid values? The documentation for `$config{osm_layers}`
+> says "in a syntax acceptable for OpenLayers.Layer.OSM.url parameter" so
+> perhaps:
+>
+>     # expected by current branch
+>     \[[!osm layers="OSM,WTF,OMG"]]
+>     \[[!osm layers="http://example.com/${z}/${x}/${y}.png,http://example.org/tiles/${z}/${x}/${y}.png"]]
+>     # current branch would misbehave with this syntax but it could be
+>     made to work
+>     \[[!osm layers="OSM, WTF, OMG"]]
+>     \[[!osm layers="""http://example.com/${z}/${x}/${y}.png,
+>       http://example.org/tiles/${z}/${x}/${y}.png"""]]
+>     # I would personally suggest whitespace as separator (split(' ', ...))
+>     \[[!osm layers="OSM WTF OMG"]]
+>     \[[!osm layers="""http://example.com/${z}/${x}/${y}.png
+>       http://example.org/tiles/${z}/${x}/${y}.png"""]]
+>
+> If you specify more than one layer, is it like "get tiles from OpenCycleMap
+> server A or B or C as a round-robin", or "draw OpenCycleMap and then overlay
+> county boundaries and then overlay locations of good pubs", or what?
+>
+>     +		layers => @layers,
+>
+> If @layers didn't have exactly one item, this would mess up argument-parsing;
+> but it has exactly one item (a reference to an array), so it works.
+> Again, if you replace @layers with $layers throughout, that would be better.
+>
+>     -        $options{'layers'} = $config{osm_layers};
+>
+> Shouldn't the default if no `$params{layers}` are given be this, rather
+> than a hard-coded `['OSM']`?
+>
+> `getsetup()` says `osm_layers` is `safe => 0`, which approximately means
+> "don't put this in the web UI, changing it could lead to a security flaw
+> or an unusable website". Is that wrong? If it is indeed unsafe, then
+> I would expect changing the same thing via \[[!osm]] parameters to be
+> unsafe too.
+>
+> I notice that `example => { 'OSM', 'GoogleSatellite' }` is wrong:
+> it should (probably) be `example => [ 'OSM', 'GoogleSatellite' ]`
+> (a list of two example values, not a map with key 'OSM' corresponding
+> to value 'GoogleSatellite'. That might be why you're having trouble
+> with this.
+>
+> "Fix the title and description of map popups"
+>
+>    +			# Rename desc to description (this matches the kml output)
+>
+> Is there a spec for this anywhere, or a parser with which it needs to be
+> compatible?
+>
+> --[[smcv]] [[!tag reviewed]]