diff --git src/main/docbkx/security.xml src/main/docbkx/security.xml
index f54f227..c7ea8a4 100644
--- src/main/docbkx/security.xml
+++ src/main/docbkx/security.xml
@@ -378,7 +378,68 @@
-
+
+Tags
+
+ Every cell can have metadata associated with it. Adding metadata in the data part of every cell would make things difficult.
+
+
+ The 0.98 version of HBase solves this problem by providing Tags along with the cell format.
+ Some of the usecases that uses the tags are Visibility labels, Cell level ACLs, etc.
+
+
+ HFile V3 version from 0.98 onwards supports tags and this feature can be turned on using the following configuration
+
+
+ hfile.format.version
+ 3
+
+ ]]>
+
+ Every cell can have zero or more tags. Every tag has a type and the actual tag byte array.
+ The types 0-31 are reserved for System tags. For example ‘1’ is reserved for ACL and ‘2’ is reserved for Visibility tags.
+
+
+ The way rowkeys, column families, qualifiers and values are encoded using different Encoding Algos, similarly the tags can also be encoded.
+ Tag encoding can be turned on per CF. Default is always turn ON.
+ To turn on the tag encoding on the HFiles use
+
+
+
+ Note that encoding of tags takes place only if the DataBlockEncoder is enabled for the CF.
+
+
+ As we compress the WAL entries using Dictionary the tags present in the WAL can also be compressed using Dictionary.
+ Every tag is compressed individually using WAL Dictionary. To turn ON tag compression in WAL dictionary enable the property
+
+
+ hbase.regionserver.wal.tags.enablecompression
+ true
+
+ ]]>
+
+ To add tags to every cell during Puts, the following apis are provided
+
+
+
+ Some of the feature developed using tags are Cell level ACLs and Visibility labels.
+ These are some features that use tags framework and allows users to gain better security features on cell level.
+
+
+ For details checkout
+
+
+ Access Control
+ Visibility labels
+
+Access Control