Page Comparison

...

name (Required). String. Either the first, last name or both must be present.
login (Optional). String. Login name of the user. If login is present, the user will be counted towards your license count.
password (Optional). String. Password of the user.
email (Optional). String. Email of the user. For users with login, email is mandatory.
virtual (Optional). True or False, For creating user with login details or not.
bill_rate (Optional). A decimal value specifying the billing rate of the new user.
cost_rate (Optional). A decimal value specifying the cost rate of the new user.
phone (Optional). A numeric value.
calendar_id (Optional). The name or ID of the work calendar with which the new user is to be created.
keywords (Optional). String.
privileged (Optional). True or False, For creating user with admin privileges or not respectively.
role_id(Optional). The name or ID of Workspace and role in the format Workspace:Role. Not specifying this will create user to play Staff role in All/Default department.
template_user_id (Optional). The ID of the user whose dashboard, favorite reports, date preferences will be copied to create the new user.
custom_field_1 (Optional). The custom field attached to user. You need to use the Formula Key of the custom field. 

...

<data>
    <item>
      <name>Joe Cole</name>
      <login>joe.cole</login>
      <password>kaboom1</password>
      <email>joe.cole@celoxis.com</email>
      <template_user_id>1738</roletemplate_user_ids>id>                
      <client_ref_no>AIQ_87</client_ref_no>             <!-- Custom field attached to user> 
    </item>
    <item>
      <name>Eva Brown</name>
      <login>eva.brown</login>
      <password>thunder45</password>
      <email>joe.cole@celoxis.com</email>
      <role_id>Support:CCA,Testing:QA</role_id>
    </item>
 </data>

In case of JSON, you should submit an array of objects with the same properties.

[
  {
    "name":"Joe Cole",
    "login":"joe.cole",
    "password":"kaboom1",
    "email":"joe.cole@celoxis.com"
    "client_ref_no":"AIQ_87"       <!-- Custom field attached to user> 
  }
  {
    "name":"MaryEva JaneBrown",
    "login":"maryeva.janebrown",
    ...
 }
]