What's the meaning of system column in views

Hi all,

I see the following for a view a_view;

# select ctid, xmin, cmin, xmax, cmax, tableoid from a_view;
ctid | xmin | cmin | xmax | cmax | tableoid
------+------+------+------+------+----------
| | | | |
| | | | |
| | | | |
| | | | |
| | | | |
| | | | |
| | | | |
| | | | |
(8 rows)

All system columns are null and seem to have no
meaning to me.
In addition it's also annoying to me e.g.

# create view aview as select ctid, * from a_table;
ERROR: name of column "ctid" conflicts with an existing system column

If there's no objection I would remove system columns
from views and allow the second example.

regards,
Hiroshi Inoue
http://w2422.nsk.ne.jp/~inoue/