diff --git a/cave_data/2012-ns-07.html b/cave_data/1623-2012-ns-07.html
similarity index 95%
rename from cave_data/2012-ns-07.html
rename to cave_data/1623-2012-ns-07.html
index cdcb6afc2..45716b3d2 100644
--- a/cave_data/2012-ns-07.html
+++ b/cave_data/1623-2012-ns-07.html
@@ -32,7 +32,7 @@ code used in the Austrian kataster e.g '1/S +' - https://expo/.survex.com/katast
 <unofficial_number>2012-ns-07</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>2012-ns-07</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-ns-07</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/cave_data/2013-03.html b/cave_data/1623-2013-03.html
similarity index 87%
rename from cave_data/2013-03.html
rename to cave_data/1623-2013-03.html
index b026b1bb2..c90d2a7bd 100644
--- a/cave_data/2013-03.html
+++ b/cave_data/1623-2013-03.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>2013-03</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>1623-2013-03</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>AntsInYourPants</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>2013-03</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>2013-03</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>1623-2013-03</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>2013-03</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>Matt Watson,  Holly Bradley, Becka Lawson</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>Logbook 2013-08-04
diff --git a/cave_data/2018-pf-01.html b/cave_data/1623-2018-pf-01.html
similarity index 91%
rename from cave_data/2018-pf-01.html
rename to cave_data/1623-2018-pf-01.html
index dd9c4536e..42e64d79c 100644
--- a/cave_data/2018-pf-01.html
+++ b/cave_data/1623-2018-pf-01.html
@@ -32,12 +32,12 @@ code used in the Austrian kataster e.g '1/S +' - https://expo/.survex.com/katast
 <unofficial_number>2018-pf-01</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>2018-pf-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>1623-2018-pf-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>
 
 <entrance>
-  <entranceslug>2018-pf-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>1623-2018-pf-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/cave_data/2018-pf-02.html b/cave_data/1623-2018-pf-02.html
similarity index 88%
rename from cave_data/2018-pf-02.html
rename to cave_data/1623-2018-pf-02.html
index e92b2ab32..8f38032c8 100644
--- a/cave_data/2018-pf-02.html
+++ b/cave_data/1623-2018-pf-02.html
@@ -32,12 +32,7 @@ code used in the Austrian kataster e.g '1/S +' - https://expo/.survex.com/katast
 <unofficial_number>2018-pf-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>2018-pf-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>2018-pf-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>1623-2018-pf-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>
 
diff --git a/cave_data/2012-ns-12.html b/cave_data/2012-ns-12.html
index 704f08e5e..94c9c827c 100644
--- a/cave_data/2012-ns-12.html
+++ b/cave_data/2012-ns-12.html
@@ -32,7 +32,7 @@ code used in the Austrian kataster e.g '1/S +' - https://expo/.survex.com/katast
 <unofficial_number>2012-ns-12</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>2012-ns-12</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></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/2012-ns-07.html b/entrance_data/1623-2012-ns-07.html
similarity index 98%
rename from entrance_data/2012-ns-07.html
rename to entrance_data/1623-2012-ns-07.html
index 82cad9263..0df38d9e1 100644
--- a/entrance_data/2012-ns-07.html
+++ b/entrance_data/1623-2012-ns-07.html
@@ -14,7 +14,7 @@
 <body>
 <entrance>
 <non_public>False</non_public>
-<slug>2012-ns-07</slug>
+<slug>1623-2012-ns-07</slug>
 <name></name>
 <entrance_description></entrance_description>
 <explorers></explorers>
diff --git a/entrance_data/2013-03.html b/entrance_data/1623-2013-03.html
similarity index 98%
rename from entrance_data/2013-03.html
rename to entrance_data/1623-2013-03.html
index e28d209b7..a7b5f37a1 100644
--- a/entrance_data/2013-03.html
+++ b/entrance_data/1623-2013-03.html
@@ -14,7 +14,7 @@
 <body>
 <entrance>
 <non_public>False</non_public>
-<slug>2013-03</slug>
+<slug>1623-2013-03</slug>
 <name></name>
 <entrance_description></entrance_description>
 <explorers></explorers>
diff --git a/entrance_data/2018-pf-02.html b/entrance_data/1623-2018-pf-02.html
similarity index 98%
rename from entrance_data/2018-pf-02.html
rename to entrance_data/1623-2018-pf-02.html
index 11e757bd9..d4fa9e924 100644
--- a/entrance_data/2018-pf-02.html
+++ b/entrance_data/1623-2018-pf-02.html
@@ -14,7 +14,7 @@
 <body>
 <entrance>
 <non_public>False</non_public>
-<slug>2018-pf-02</slug>
+<slug>1623-2018-pf-02</slug>
 <name></name>
 <entrance_description></entrance_description>
 <explorers></explorers>
diff --git a/entrance_data/2018-pf-01.html b/entrance_data/2018-pf-01.html
deleted file mode 100644
index 51700a790..000000000
--- a/entrance_data/2018-pf-01.html
+++ /dev/null
@@ -1,54 +0,0 @@
-<!DOCTYPE html>
-<!-- Only put one entrance in this file -->
-<!-- This file is generated using the form documented at /handbook/survey/caveentry.html -->
-<!-- If you edit this file by hand, make sure you update the database by doing a full data import -->
-
-    <!-- See http://expo.survex.com/handbook/survey/caveentryfields.html for current details on filling in this form -->
-    <!-- there is 1 required field: slug. The entrance will not appear without that. -->
-    <!-- ALWAYS use &uuml; for u+Umlaut and &ouml; for o+umlaut eg H&ouml;hle for Hohle and Gl&uuml;ck for Gluck-->
-
-<html lang="en">
-<head>
-<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
-</head>
-<body>
-<entrance>
-<non_public>False</non_public>
-<slug>2018-pf-01</slug>
-<name></name>
-<entrance_description>rriving at the Big Cairn (GPS coords UTM: 33T 0411542, 5282881) which is on the Tunnocks path, we followed the 2005 instructions and veered left on an alleged heading towards the fabled caves 2004-18, 17, and 16 . Directly off the Tunnocks path we got distracted as we came upon 3 shafts which were not on the GPS catalogue: we named them 2018-PF-01 (which we tagged; see our survey of the same day), 2018-PF-02 (which we tagged the next day with Wookey; undescended), and 2018-PF-03 (which Paul tagged some days later)</entrance_description>
-<explorers></explorers>
-<map_description></map_description>
-<location_description></location_description>
-<approach></approach>
-<underground_description></underground_description>
-<photo></photo>
-<!-- marking options: P  = Paint,
-                      P? = Paint (?),
-                      T  = Tag,
-                      T? = Tag (?),
-                      R  = Retagged,
-                      S  = Spit,
-                      S? = Spit (?),
-                      U  = Unmarked,
-                      ?  = Unknown" -->
-<marking>T</marking> 
-<marking_comment></marking_comment>
-<!-- findability options: ? = To be confirmed ...,
-                          S = Surveyed,
-                          L = Lost,
-                          R = Refindable" -->
-<findability></findability>
-<findability_description></findability_description>
-<alt>1857</alt>
-<northing>0411526</northing>
-<easting>5282885</easting> 
-<tag_station></tag_station>
-<exact_station></exact_station>
-<other_station></other_station>
-<other_description></other_description>
-<bearings></bearings>
-<url></url>
-</entrance>
-</body>
-</html>
