c# - .NET callback as function parameter? -

i'm working on project has api , 1 of function's signature follows:

public system.threading.tasks.task<farmersmarket.service.results> zipsearchasync(string zip, string callback) {     return base.channel.zipsearchasync(zip, callback); } 

the string callback parameter confusing me. .net delegate? same javascript callback?

update: i'm working api: http://search.ams.usda.gov/farmersmarkets/v1/svcdesc.html. there's object called "marketserviceclient" , that's documentation.

given api can consumed via ajax, imagine callback parameter server write jsonp results when serving jsonp.