Spanish to English Law/Patents Construction / Civil Engineering Building contract

Hello,
Does anyone have any idea if this is the name of a particular certificate or if it is just lettering that just needs to be transcribed in the translation?
It refers to a type of contract in a clause regarding a contractor's final settlement fee for work carried out.
Please find the certificate in question referred to in the full sentence below:
El SUBCONTRATISTA declara en este acto que con el cobro de la certificación de B.I. 5.925,40 y fecha 30 de Diciembre de 2016 en la forma y modo estipulados en el contrato, habrá percibido el total importe de los trabajos a él encomendados, sin que quede pendiente reclamación alguna por su parte y declarando su total conformidad con los cobros realizados, a excepción de las retenciones contractuales establecidas.

My attempt was:
THE SUBCONTRACTOR hereby declares that with the certification fee of B.I. 5.925,40 dated 30 December 2016 in the form and manner stipulated in the contract, it will have received the total amount for the works entrusted to it, without any outstanding claims remaining on its part, and declares its satisfaction with the settlements made, at the exception of established contractual withholdings.