diff --git a/cave_data/2009-02.html b/cave_data/1623-2009-02.html
similarity index 85%
rename from cave_data/2009-02.html
rename to cave_data/1623-2009-02.html
index 36aa19cd9..a9e6aab6f 100644
--- a/cave_data/2009-02.html
+++ b/cave_data/1623-2009-02.html
@@ -10,7 +10,7 @@
 <body>
 <cave>
 <non_public>False</non_public><!-- 'False' or 'True'. True if the cave should only be visible to logged-in users. Caves are normally public, so enter 'False' unless you know otherwise. -->
-<caveslug>2009-02</caveslug><!--(Required). Internal I.D. used to refer to this cave in entrance data files. Typically the same as the filebase, e.g. '1623-195'  -->
+<caveslug>1623-2009-02</caveslug><!--(Required). Internal I.D. used to refer to this cave in entrance data files. Typically the same as the filebase, e.g. '1623-195'  -->
 <official_name>Schneeh&uuml;hnh&ouml;hle</official_name><!-- Name of the cave (normally in German)  Use &uuml; for u+Umlaut and &ouml; for o+umlaut eg H&ouml;hle for Hohle and Gl&uuml;ck for Gluck-->
 <area>1623</area><!-- the CUCC-defined areas shown in http://expo.survex.com/areas.htm -->
 <kataster_code></kataster_code><!-- 'length-or-depth/type exploration'
@@ -32,14 +32,10 @@ code used in the Austrian kataster e.g '1/S +' - https://expo/.survex.com/katast
 <unofficial_number>2009-02</unofficial_number><!-- (Either this or kataster_number is required). Initial temporary cave ID used until kataster number is allocated e.g. '2012-DD-01'-->
 
 <entrance>
-  <entranceslug>2009-02</entranceslug><!-- Internal ID to refer to each entrance instance in the entrance files (typically the same as that filename (e.g. 1623-161c). Matches the 'slug' field in the entrance file -->
+  <entranceslug>1623-2009-02</entranceslug><!-- Internal ID to refer to each entrance instance in the entrance files (typically the same as that filename (e.g. 1623-161c). Matches the 'slug' field in the entrance file -->
   <letter></letter><!--Leave blank for single-entrance cave. If there is more than one entrace then the letter needs to be given. Generally matches the entranceslug ID.  -->
 </entrance>
 
-<entrance>
-  <entranceslug>2009-02</entranceslug><!-- Internal ID to refer to each entrance instance in the entrance files (typically the same as that filename (e.g. 1623-161c). Matches the 'slug' field in the entrance file -->
-  <letter></letter><!--Leave blank for single-entrance cave. If there is more than one entrace then the letter needs to be given. Generally matches the entranceslug ID.  -->
-</entrance>
 
 <explorers>Frank Tully</explorers><!-- 'CUCC Expo' and year(s) of exploration. To distinguish from caves explored by foreign groups. Individual names can be given too if it was a small cave. -->
 <underground_description></underground_description><!-- Underground description. (description of approach and entrance goes in entrance file). For a small cave this will be the entire description. For larger caves it will be the front page of the description, or a short intro, containing links to other pages with the cave description in, or even nothing but a link. -->
@@ -48,8 +44,8 @@ code used in the Austrian kataster e.g '1/S +' - https://expo/.survex.com/katast
 <survey></survey><!-- Drawn-up surveys. Scans of paper surveys or images/PDFs of electronic surveys. Should include HTML to display current plan and elevation, with links to larger versions (See section on URLs and files). Could list links to multiple years of survey, or even a separate survey page if it's complicated enough. -->
 <kataster_status></kataster_status>
 <underground_centre_line></underground_centre_line><!-- 'In dataset' if it is in the survex dataset. Blank if not, or notes about status such as 'surveyed, but no entrance fix so not yet in dataset'. -->
-<notes>scanned survey notes and survex file but no entrance location data.
-<br>
+<notes>scanned survey notes and survex file but no entrance location data.
+<br>
 No relevant logbook entry on this date either. Did Frank do this entirely on his own?</notes><!-- Normally empty, but place for anything else that should be noted, such as info on cave maybe being a duplicate, or lost -->
 <length></length><!-- Cave length. Can be left blank and system should fill it in automatically from survey data (it doesn't yet) -->
 <depth></depth><!--Cave depth. Can be left blank and system should fill it in automatically from survey data (it doesn't yet)  -->
diff --git a/cave_data/2012-OW-01.html b/cave_data/1623-2012-OW-01.html
similarity index 92%
rename from cave_data/2012-OW-01.html
rename to cave_data/1623-2012-OW-01.html
index 4d9cb9543..c2744a8c5 100644
--- a/cave_data/2012-OW-01.html
+++ b/cave_data/1623-2012-OW-01.html
@@ -10,7 +10,7 @@
 <body>
 <cave>
 <non_public>False</non_public><!-- 'False' or 'True'. True if the cave should only be visible to logged-in users. Caves are normally public, so enter 'False' unless you know otherwise. -->
-<caveslug>2012-OW-01</caveslug><!--(Required). Internal I.D. used to refer to this cave in entrance data files. Typically the same as the filebase, e.g. '1623-195'  -->
+<caveslug>1623-2012-OW-01</caveslug><!--(Required). Internal I.D. used to refer to this cave in entrance data files. Typically the same as the filebase, e.g. '1623-195'  -->
 <official_name>Birth Control Chamber</official_name><!-- Name of the cave (normally in German)  Use &uuml; for u+Umlaut and &ouml; for o+umlaut eg H&ouml;hle for Hohle and Gl&uuml;ck for Gluck-->
 <area>1623</area><!-- the CUCC-defined areas shown in http://expo.survex.com/areas.htm -->
 <kataster_code></kataster_code><!-- 'length-or-depth/type exploration'
@@ -37,7 +37,7 @@ code used in the Austrian kataster e.g '1/S +' - https://expo/.survex.com/katast
 </entrance>
 
 <entrance>
-  <entranceslug>2012-OW-01</entranceslug><!-- Internal ID to refer to each entrance instance in the entrance files (typically the same as that filename (e.g. 1623-161c). Matches the 'slug' field in the entrance file -->
+  <entranceslug>1623-2012-OW-01</entranceslug><!-- Internal ID to refer to each entrance instance in the entrance files (typically the same as that filename (e.g. 1623-161c). Matches the 'slug' field in the entrance file -->
   <letter></letter><!--Leave blank for single-entrance cave. If there is more than one entrace then the letter needs to be given. Generally matches the entranceslug ID.  -->
 </entrance>
 
diff --git a/entrance_data/2009-02.html b/entrance_data/1623-2009-02.html
similarity index 98%
rename from entrance_data/2009-02.html
rename to entrance_data/1623-2009-02.html
index 7890bb392..097edb259 100644
--- a/entrance_data/2009-02.html
+++ b/entrance_data/1623-2009-02.html
@@ -14,7 +14,7 @@
 <body>
 <entrance>
 <non_public>False</non_public>
-<slug>2009-02</slug>
+<slug>1623-2009-02</slug>
 <name>1623-2009-02</name>
 <entrance_description></entrance_description>
 <explorers></explorers>
diff --git a/entrance_data/2012-OW-01.html b/entrance_data/1623-2012-OW-01.html
similarity index 98%
rename from entrance_data/2012-OW-01.html
rename to entrance_data/1623-2012-OW-01.html
index 0f7c982a4..06698f5ef 100644
--- a/entrance_data/2012-OW-01.html
+++ b/entrance_data/1623-2012-OW-01.html
@@ -14,7 +14,7 @@
 <body>
 <entrance>
 <non_public>False</non_public>
-<slug>2012-OW-01</slug>
+<slug>1623-2012-OW-01</slug>
 <name></name>
 <entrance_description>See scanned notes, not typed up</entrance_description>
 <explorers></explorers>
