| Code | Display | Definition |
| number | Number | Search parameter SHALL be a number (a whole number, or a decimal). |
| date | Date/DateTime | Search parameter is on a date/time. The date format is the standard XML format, though other formats may be supported. |
| string | String | Search parameter is a simple string, like a name part. Search is case-insensitive and accent-insensitive. May match just the start of a string. String parameters may contain spaces. |
| token | Token | Search parameter on a coded element or identifier. May be used to search through the text, displayname, code and code/codesystem (for codes) and label, system and key (for identifier). Its value is either a string or a pair of namespace and value, separated by a "|", depending on the modifier used. |
| reference | Reference | A reference to another resource. |
| composite | Composite | A composite search parameter that combines a search on two values together. |
| quantity | Quantity | A search parameter that searches on a quantity. |
| uri | URI | A search parameter that searches on a URI (RFC 3986). |