--- a/ThemeCfg.wiki	Thu May 16 18:50:50 2019 +0100
+++ b/ThemeCfg.wiki	Thu May 16 22:40:51 2019 +0100
@@ -57,7 +57,7 @@
 
 Syntax when you only need 1 buried rectangle:
 
-<code>Values: filename, max, buriedrec, minvisible, visiblerec</code>
+<code>Values: filename, max, buriedrect, minvisible, visiblerec</code>
 
 Syntax when you want to use multiple buried rectangles:
 
@@ -69,6 +69,20 @@
 
 The large rectangle shows a `visiblerects` and the small one shows a `buriedrects`.
 
+=== `overlays` ===
+An overlay is an extension of an object. It is an image that is drawn relative to the position of an object that was already placed. Overlays create land just like objects do, but unlike objects, they are drawn on top of the main landmass, instead of behind it. An object can have multiple overlays.
+
+This key allows you to assign 1 or more overlays to a given object. If multiple overlays are used, all overlays are drawn whenever the object is placed. This key must be added after the definition of the object you want to add overlays for.
+
+<code>Values: object_filename, overlay_count, x_offset_1, y_offset_1, overlay_filename_1, ...</code>
+
+ * `object_filename`: File name of the object to which this overlay applies
+ * `overlay_count`: Number of overlays for this object
+ * `x_offset_1`: X position offset of the overlay image relative to the object. Note: The top left corner acts as the image origin
+ * `y_offset_1`: Y position offset of the overlay
+ * `overlay_filename_1`: File name of the overlay image to use
+ * You must repeat the last 3 arguments if `overlay_count` is greater than 1; each overlay needs its own offset and file name.
+
 === `spray` ===
 There may be several spray keys in the file, each one representing one spray object.
 The `name` is the case-sensitive name of the PNG file (without the file name suffix) of the graphics file, and `number` is the rough number of instances of this spray that may be added to the map. The number is the average number of sprays that are normally placed on a random medium-sized island. For larger and smaller landscapes, this number will be automatically scaled up or down. Please note that this number only specifies a rough goal, the actual number of created sprays may vary and you may have to play a bit with this number in order to find a good value.