From Source:

DigixDAO (DGD) will credit the Ethereum Classic (ETC) held within DigixDAO from the Ethereum (ETH) hard fork back to DGD holders. Bittrex users will be credited approximately 0.23255 ETC for each DGD token held in their exchange accounts at ETH block 3,800,000. The block is estimated to occur at approximately 5/31/2017.

Bittrex will credit the ETC tokens and enable the market when the smart contract claim process has been completed by Bittrex. The DGD market will be re-enabled and all orders cancelled within 48 hours after ETH block 3,800,000.

Note: Bittrex will be closing our DGD wallet and market within two hours of the ETH block 3,800,000 to take accurate snapshots of balances. If your deposits are not settled (e.g. marked as pending) by 5/31/2017, you may not be credited with ETC.

Please note that Bittrex will need to wait for the DigixDAO to successfully complete their own snapshot of ETH block 3,800,000 and the deployment of the ETC redemption smart contract.

We would like to thank the DigixDAO team for working closely with us.

The DigixDAO team has put out a detailed description of the process:

ANN: ETC Refund from DigixDAO — Snapshot Block fixed at #3,800,000

https://medium.com/@Digix/etc-refund-from-digixdao-snapshot-block-fixed-at-block-3-800-000-36e40cc13e48

Digix ETC Redemption User Guide

https://github.com/DigixGlobal/etc-redemption/blob/master/guide/GUIDE.md