line datatype

Probably the most succinct explanation would be to copy & paste from the
terminal...

tjhart=> create table a_line( foo line );
CREATE
tjhart=> insert into a_line ( foo ) values( '(0,0), (1,1)' );
ERROR: line not yet implemented
tjhart=> select version();
version
---------------------------------------------------------------------
PostgreSQL 7.2.1 on powerpc-apple-darwin5.3, compiled by GCC 2.95.2
(1 row)

The documentation (datatype-geometric.html) indicates both a 'line' type
and an 'lseg' type in the summary table at the top of the page. The same
code above using the type 'lseg' in place of 'line' works just fine.

Why can I create a table with a column of type 'line' if I can't insert
into it?