PG 8.4 and identity columns

Hello PGlist,
We are interested in migrate some data with identity/sequential columns
from a non PG database into PG database , tables with identity columns.
 First Q is : are system generated/identity columns values supported in
PG8.4 if yes,
I would like to know if there is a option to control this values:  aka :
 can we set the identity value "off" while we are inserting some already
generated values and next turn "on" the identity column option in PG ?
next Q : can we set the gap of the values, and can we set what the next
generated value /start value to our choice?
Thank you
Isabella

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Isabella A. Ghiurea

Isabella.Ghiurea@nrc-cnrc.gc.ca
Canadian Astronomy Data Centre |http://www.nrc-cnrc.gc.ca/eng/services/hia/data-centre.html
National Research Council of Canada, Herzberg Institute of Astrophysics
5071 West Saanich Road, Victoria BC V9E 2E7, Canada
Phone: 250 363-3446 fax: 250 363-0045