The following instructions can help you analyze an XML API schema.
agent_input.xsd schema. It lists all supported operator elements within the packet element. For example,
On the above figure, complex data type RequestPacketType lists all supported operator elements. These operators are: server, customer, webspace, etc. Each operator has a matching request data type (the type attribute). This data type describes the structure of the operator.
agent_input.xsd lists all subsequent schemas as follows:
The schema name contains the name of the operator you need and the _input suffix.
client_input.xsd schema matching the customer operator.
The customer operator is described by type ServerOperatorType (highlighted). To see its structure, click the + sign to the left and expand the section.
agent_input.xsd schema) declares operations that can be applied to the relevant object. 
client_input.xsd schema as follows:
All nested elements (operation parameters) are described by specific data types. You can find their definitions either in the same schema, or in the included schema:

Thus, when you analyse the schemas, the approach is as follows: start with the main schema to choose the operator and drill down to the subsequent data types that can be found in the included schemas.