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PSU headers

Some operations declare PSU-IP-Address and PSU-User-Agent as required or optional headers. They tell ZTL and the bank whether an end user is actively present.

When the user is present:

  • forward the IP address observed for the current user session;
  • forward the user agent from the current browser request; and
  • validate and transmit the values at request time.

Never fabricate a value, send your server’s IP or user agent as the PSU, replay a value from a previous session, or use a value stored in your database to make an unattended request appear user-present.

When no user is present, omit optional PSU headers. Do not call an operation that requires them unless the user is actively participating and your application can forward the current values.

Check each generated operation because the requirement differs by endpoint and phase.