| Membership Code | Concept Code | Description | Code System | Code System Version |
|---|---|---|---|---|
| ASKU | ASKU | asked but unknown | NullFlavor | 2.01.4 |
| MSK | MSK | masked | NullFlavor | 2.01.4 |
| NA | NA | not applicable | NullFlavor | 2.01.4 |
| NASK | NASK | not asked | NullFlavor | 2.01.4 |
| NAV | NAV | temporarily unavailable | NullFlavor | 2.01.4 |
| NI | NI | NoInformation | NullFlavor | 2.01.4 |
| NINF | NINF | negative infinity | NullFlavor | 2.01.4 |
| OTH | OTH | other | NullFlavor | 2.01.4 |
| PINF | PINF | positive infinity | NullFlavor | 2.01.4 |
| QS | QS | QS | NullFlavor | 2.01.4 |
| TRC | TRC | TRC | NullFlavor | 2.01.4 |
| UNK | UNK | unknown | NullFlavor | 2.01.4 |
| DER | DER | derived | NullFlavor | 2.01.4 |
| INV | INV | invalid | NullFlavor | 2.01.4 |
| UNC | UNC | un-encoded | NullFlavor | 2.01.4 |