An open edition is the opposite of a limited edition. It has some drawbacks and advantages depending on how you view it.
An open edition is an unlimited edition by definition, and often the copies have no numbers. The result tends to be less expensive than limited editions. Note that this may simply be because because the publishing of the art is such that every one piece is produced to order, rather than all at once.
Keep in mind that open editions may then be more rare than limited editions, though you have to be prepared to gamble a little as a collector if you cannot establish how many copies will come into existence.
