I would like to know what the FHIR standard says about defining custom standard parameters (https://www.hl7.org/fhir/search.html#standard). Lets say I want a search parameter mystandardparameter which is a search parameter which applies to all searches on my server. Should I use and underscore ("") or just name it mystandardparameter? Without the underscore it seems not to be consistent which how the standard parameters defined by FHIR are named and also it could potentially collide with domain resource fields. On the other hand this example seems to define custom standard parameters with names stateid and count: https://www.hl7.org/fhir/http.html#paging. So which way should I go?
Best regards, Allan