appels de provisions

French to English Bus/Financial Accounting Annual financial statements

Here is the context:

It comes under Valorisation des encours (valuation of outstanding amounts)

Les Produits Constatés d'Avance correspondent aux appels de provisions sur facturation pour les chantiers en cours

I have translated the sentence as follows, but feel very unsure of it:

'Prepaid income applies to APPELS DE PROVISIONS (calls for reserves )for work in progress upon submission of an invoice. '