What is syntax for "Usages" dictionary?

Albert, assuming you are using the Orion SDK for Python to create the custom property, you could use a syntax like this to specify the Usages:

import requests
from orionsdk import SwisClient


def main():
    server = 'localhost'
    username = 'admin'
    password = ''

    swis = SwisClient(server, username, password)

    usages = {
        "IsForAlerting": False
    }

    swis.invoke(
        'Orion.NodesCustomProperties',
        'CreateCustomProperty',
        'MyCustomProperty', 'this is my description', 'string', 4000, None, None, None, None, None, None, usages)

requests.packages.urllib3.disable_warnings()


if __name__ == '__main__':
    main()

If you're using a different language to leverage the Orion SDK, let me know, and I'll try to get you a sample for your language of choice.