1- <!-- $Header: /cvsroot/pgsql/doc/src/sgml/ref/create_cast.sgml,v 1.2 2002/08/11 17:44:12 petere Exp $ -->
1+ <!-- $Header: /cvsroot/pgsql/doc/src/sgml/ref/create_cast.sgml,v 1.3 2002/09/01 02:37:02 tgl Exp $ -->
22
33<refentry id="SQL-CREATECAST">
44 <refmeta>
@@ -28,8 +28,8 @@ CREATE CAST (<replaceable>sourcetype</replaceable> AS <replaceable>targettype</r
2828
2929 <para>
3030 <command>CREATE CAST</command> defines a new cast. A cast
31- specifieswhich function can be invoked when a conversion between
32- two data types is requested . For example,
31+ specifieshow to perform a conversion between
32+ two data types. For example,
3333<programlisting>
3434SELECT CAST(42 AS text);
3535</programlisting>
@@ -49,7 +49,7 @@ SELECT CAST(42 AS text);
4949 </para>
5050
5151 <para>
52- A cast can marked <literal>AS ASSIGNMENT</>, which means that it
52+ A cast canbe marked <literal>AS ASSIGNMENT</>, which means that it
5353 can be invoked implicitly in any context where the conversion it
5454 defines is required. Cast functions not so marked can be invoked
5555 only by explicit <literal>CAST</>,
@@ -72,7 +72,7 @@ INSERT INTO foo(f1) VALUES(42);
7272 <productname>PostgreSQL</productname> to choose surprising
7373 interpretations of commands, or to be unable to resolve commands at
7474 all because there are multiple possible interpretations. A good
75- rule of thumb is to make cast implicitly invokable only for
75+ rule of thumb is to makea cast implicitly invokable only for
7676 information-preserving transformations between types in the same
7777 general type category. For example, <type>int2</type> to
7878 <type>int4</type> casts can reasonably be implicit, but be wary of
@@ -161,9 +161,10 @@ INSERT INTO foo(f1) VALUES(42);
161161 <para>
162162 Prior to PostgreSQL 7.3, every function that had the same name as a
163163 data type, returned that data type, and took one argument of a
164- different type was automatically a cast function. Thissystem has
164+ different type was automatically a cast function. Thisconvention has
165165 been abandoned in face of the introduction of schemas and to be
166- able to store binary compatible casts. The built-in cast functions
166+ able to represent binary compatible casts in the catalogs. The built-in
167+ cast functions
167168 still follow this naming scheme, but they have to be declared as
168169 casts explicitly now.
169170 </para>
@@ -175,7 +176,7 @@ INSERT INTO foo(f1) VALUES(42);
175176
176177 <para>
177178 To create a cast from type <type>text</type> to type
178- <type>int </type> using the function <literal>int4(text)</literal>:
179+ <type>int4 </type> using the function <literal>int4(text)</literal>:
179180<programlisting>
180181CREATE CAST (text AS int4) WITH FUNCTION int4(text);
181182</programlisting>