# Client supplied identifiers

### Identifiers

<DocTable
  headers={["Tag", "Name", "Defined in", "Echoed back", "Description"]}
  widths={[undefined, "15%", "25%", "30%"]}
  rows={[
    [
      "320",
      "[SecurityReqID](https://www.onixs.biz/fix-dictionary/4.4/tagNum_320.html)",
      "[Symbol List Request `<x>`](/trading/fix/market-data/exchange-bound-messages/symbol-list-request)",
      "[Symbol List `<y>`](/trading/fix/market-data/client-bound-messages/symbol-list)",
      "The client's symbol list request identifier. Gemini does not enforce uniqueness although the FIX protocol recommends it.",
    ],
    [
      "262",
      "[MDReqID](https://www.onixs.biz/fix-dictionary/4.4/tagNum_262.html)",
      "[Market Data Request `<V>`](/trading/fix/market-data/exchange-bound-messages/market-data-request)",
      "[Market Data – Snapshot/Full Refresh `<W>`](/trading/fix/market-data/client-bound-messages/market-data-snapshot-full-refresh)\n\n \u00A0 \n\n[Market Data – Incremental Refresh `<X>`](/trading/fix/market-data/client-bound-messages/market-data-incremental-refresh)\n\n \u00A0 \n\n[Market Data Request Reject `<Y>`](/trading/fix/market-data/client-bound-messages/market-data-request-reject)",
      "The client's market data request identifier. Gemini requires uniqueness per active FIX session. A [Market Data Request `<V>`](/trading/fix/market-data/exchange-bound-messages/market-data-request) message with a duplicate [MDReqID `<262>`](https://www.onixs.biz/fix-dictionary/4.4/tagNum_262.html) value during the current active FIX session will be rejected using a [Market Data Request Reject `<Y>`](/trading/fix/market-data/client-bound-messages/market-data-request-reject) with the [MDReqRejReason `<281>`](https://www.onixs.biz/fix-dictionary/4.4/tagNum_281.html) field set to `1` = Duplicate [MDReqID `<262>`](https://www.onixs.biz/fix-dictionary/4.4/tagNum_262.html).",
    ],
  ]}
/>