Existing Wording: In order to save a client from doing a series of search operations, reference parameters may be "chained" by appending them with a period (.) followed by the name of a search parameter defined for the target resource. This can be done recursively, following a logical path through a graph of related resources, separated by ".". For instance, given that the resource DiagnosticReport has a search parameter namedsubject, which is usually a reference to a Patient resource, and the Patient resource includes a parameter name which searches on patient name, then the search GET [base]/DiagnosticReport?subject.name=peter

Proposed Wording: In order to save a client from doing a series of search operations, reference parameters may be "chained" by prefixing the parameter value with the name of a search parameter defined for the target resource, proceeded by a ":". This can be done recursively, following a logical path through a graph of related resources, separated by ".". For instance, given that the resource DiagnosticReport has a search parameter namedsubject, which is usually a reference to a Patient resource, and the Patient resource includes a parameter name which searches on patient name, then the search GET [base]/DiagnosticReport?subject=name:peter

Comment:

In line with feedback regarding modifiers, we similarly propose that chained parameters be implemented wthin the query parameter value string, in a similar manner to the proposed modifier syntax, to support the client needing to parse the values while still understanding the base parameter.