List of actual attributes which can be specified
In getMObjects » Marketo Developers you list a number of attribute names I can use to specify criteria for pulling MObjects (Opportunities, specifically), like "Created At" or "Updated At". But what are the actual names I should use when I build the SOAP request? If I use, verbatim, "Created At" (or any other creative variations on that name that I can think of), I get back an error: "attribute map field with key Created At not found".
Thanks!