Multileg instrument's individual security’s SecurityAltIDSource.
See SecurityAltIDSource (456) field for description
| Code | Meaning | 
|---|---|
| 1 | CUSIP | 
| 2 | SEDOL | 
| 3 | QUIK | 
| 4 | ISIN | 
| 5 | RIC | 
| 6 | ISO Currency Code (ISO 4217) | 
| 7 | ISO Country Code | 
| 8 | Exchange symbol | 
| 9 | Consolidated Tape Association (CTA) Symbol (SIAC CTS/CQS line format) | 
| A | Bloomberg Symbol | 
| B | Wertpapier | 
| C | Dutch | 
| D | Valoren | 
| E | Sicovam | 
| F | Belgian | 
| G | "Common" (Clearstream and Euroclear) | 
| H | Clearing house / Clearing organization | 
| I | ISDA/FpML product specification (XML in SecurityXML(1185)) | 
| J | Option Price Reporting Authority | 
| K | ISDA/FpML product URL (URL in SecurityID(48)) | 
| L | Letter of credit | 
| M | Marketplace-assigned Identifier | 
| N | Markit RED entity CLIP | 
| P | Markit RED pair CLIP | 
| Q | CFTC commodity code | 
| R | ISDA Commodity Reference Price | 
| S | Financial Instrument Global Identifier | 
| T | Legal entity identifier | 
| U | Synthetic | 
| V | Fidessa Instrument Mnemonic (FIM) | 
| W | Index name | 
| X | Uniform Symbol (UMTF Symbol) | 
| Y | Digital Token Identifier (ISO 24165) |