| 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, display, 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 (Reference or canonical). |
| 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). |
| special |
Special |
Special logic applies to this parameter per the description of the search parameter. |