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-rw-r--r--doc/src/sgml/datatype.sgml36
1 files changed, 26 insertions, 10 deletions
diff --git a/doc/src/sgml/datatype.sgml b/doc/src/sgml/datatype.sgml
index 0b969eaa22e..d05c93058a0 100644
--- a/doc/src/sgml/datatype.sgml
+++ b/doc/src/sgml/datatype.sgml
@@ -1,4 +1,4 @@
-<!-- $PostgreSQL: pgsql/doc/src/sgml/datatype.sgml,v 1.228 2008/09/11 15:27:30 tgl Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/datatype.sgml,v 1.229 2008/10/03 15:37:18 petere Exp $ -->
<chapter id="datatype">
<title id="datatype-title">Data Types</title>
@@ -3187,23 +3187,39 @@ SELECT person.name, holidays.num_weeks FROM person, holidays
</indexterm>
<para>
- The <type>macaddr</> type stores MAC addresses, i.e., Ethernet
- card hardware addresses (although MAC addresses are used for
- other purposes as well). Input is accepted in various customary
- formats, including
+ The <type>macaddr</> type stores MAC addresses, known for example
+ from Ethernet card hardware addresses (although MAC addresses are
+ used for other purposes as well). Input is accepted in the
+ following formats:
<simplelist>
+ <member><literal>'08:00:2b:01:02:03'</></member>
+ <member><literal>'08-00-2b-01-02-03'</></member>
<member><literal>'08002b:010203'</></member>
<member><literal>'08002b-010203'</></member>
<member><literal>'0800.2b01.0203'</></member>
- <member><literal>'08-00-2b-01-02-03'</></member>
- <member><literal>'08:00:2b:01:02:03'</></member>
+ <member><literal>'08002b010203'</></member>
</simplelist>
- which would all specify the same
- address. Upper and lower case is accepted for the digits
+ These examples would all specify the same address. Upper and
+ lower case is accepted for the digits
<literal>a</> through <literal>f</>. Output is always in the
- last of the forms shown.
+ first of the forms shown.
+ </para>
+
+ <para>
+ IEEE Std 802-2001 specifies the second shown form (with hyphens)
+ as the canonical form for MAC addresses, and specifies the first
+ form (with colons) as the bit-reversed notation, so that
+ 08-00-2b-01-02-03 = 01:00:4D:08:04:0C. This convention is widely
+ ignored nowadays, and it is only relevant for obsolete network
+ protocols (such as Token Ring). PostgreSQL makes no provisions
+ for bit reversal, and all accepted formats use the canonical LSB
+ order.
+ </para>
+
+ <para>
+ The remaining four input formats are not part of any standard.
</para>
</sect2>