diff --git a/cadc-tap-server-pg/README.md b/cadc-tap-server-pg/README.md
index fc11bed0..91a04c0f 100644
--- a/cadc-tap-server-pg/README.md
+++ b/cadc-tap-server-pg/README.md
@@ -1,5 +1,16 @@
 # cadc-tap-server-pg 1.0.0
 
-Offers PostgreSQL support to handle datatype conversions in ADQL.
+Offers PostgreSQL support to handle datatype conversions and ADQL 
+transformations for a PostgreSQL+pgsphere backend database.
 
-See [the example](example) for a sample implementation.
+The `ca.nrc.cadc.tap.pg.PostgresDataTypeMapper` extends the default `BasicDataTypeMapper`
+with pg+phsphere specific datatype support.
+
+The `ca.nrc.cadc.tap.writer.format` package provides a FormatFactory and Format implementations
+to support pg+phsphere specific datatypes.
+
+The `ca.nrc.cadc.tap.parser` package provides various extensions of the `cadc-adql` ADQL 
+parser to support pg+phsphere specific ADQL transformations.
+
+## example usage
+The `youcat` TAP service makes use of all the features of this library.