The check is issued by the node that provides the service. The check contains a description of the service, its cost, and, optionally, some other additional data. The check is signed by the consumer and the seller and then used in conditional transactions.
Structure of the check:
Receipt:
size: 6693
ext size: 0
Info: units: 0x00000000000000f0
uid: 0x0000000000000001
units type: SERV_UNIT_SEC
value: 0.0000000000000002 (200)size - size of the receipt in bytes
ext size - size of the extended receipt data in bytes
units - quantity of provided service (seconds or megabytes)
uid - unique ID of paid service (for VPN is 1)
units type - type of the units:
SERV_UNIT_SEC - seconds
SERV_UNIT_B - bytes
value - sum value for paying check