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FAQ

Which FIX version does MEX Exchange use?​

FIX 4.4. BeginString (tag 8) must be FIX.4.4.

How many sessions do I need?​

Two per role: a market data session and an orders session. They are paired. Market data requests are rejected, or in the maker case not consumed, unless the orders session is logged in. Both use the same credentials with different SenderCompID values.

Who initiates the connection?​

The member firm. MEX Exchange is the acceptor for both takers and makers.

What order types can a taker send?​

Limit and market orders with DAY, IOC or FOK time in force. Resting DAY limit orders can be amended with an Order Cancel Replace Request and cancelled with an Order Cancel Request. Quantity is always expressed in the base currency of the symbol.

What happens to my orders if my session drops?​

For takers, all open orders are cancelled on logout or disconnect. Always log out before disconnecting.

Does the taker market data feed send snapshots?​

No. The book is delivered as Market Data Incremental Refresh messages only. The initial book arrives as a stream of New entries after you subscribe, and resends are not supported, so resubscribe to rebuild the book after a gap.

What does a maker receive?​

Fill-or-kill limit orders, one at a time, each answered with an Execution Report. Makers publish prices as Market Data Snapshot Full Refresh and Market Data Incremental Refresh messages, tagged with a TradingSessionID that identifies the liquidity stream.

Which instruments are supported?​

FX spot and non-deliverable forwards. Instruments are identified by symbol, SecurityType (FXSPOT or FXNDF) and, for tenors, SettlType or SettlDate. The supported tenor list is in each specification's appendix.

How do I get credentials or a test environment?​

Through MEX Exchange onboarding. See Request access.

Which specification version should I build against?​

The latest, marked Latest in the sidebar under FIX Specifications. Each version is also a PDF, downloadable from the top of its page, and the PDF is the document you certify against. New versions are announced in the Changelog with the date from which they become mandatory.