English to Spanish Bus/Financial Finance (general) BANK GUARANTEE

Hola a todos:

En un escrito de Bank Guarantee de una entidad bancaria:

PAYMENT IS AVAILABLE BY BENEFICIARY FIRST WRITTEN DEMAND VIA SWIFT WIRE SYSTEM, DEMAND HEREUNDER MUST BE MARKED, DRAWN UNDER THE LETTER OF GUARANTEE NUMBER X.

WE ENGAGE WITH YOU THAT THE DEMAND DRAFT UNDER AND IN COMPLIANCE WITH THE TERMS OF THIS LETTER OF GUARANTEE, SHALL BE DULY HONOURED ON DATE OF PRESENTATION TO US, THIS LETTER OF GUARANTEE IS SUBJECT TO THE UNIFORM CUSTOMS AND PRACTICE FOR DOCUMENTARY CREDITS, INTERNATIONAL CHAMBER OF COMMERCE, PARIS FRANCE, PUBLICATION 500, LATEST REVISION.

¿Alguien sabe a qué se refiere demand y demand draft en este contexto? ¿letra de cambio tendría sentido?

¡Gracias de antemano!