Particulars of Claim is simply the name of the document in which a Claimant sets down the details of what he is claiming and the grounds on which he claims it.
Often this is amended during the case as further aspects of the claim come to light or as parts are dropped.
I prefer requête as this is specifically a document that applies to a Claimant
Also modifiée/modification seems more appropriate for amended
NIGÉRIA c. CAMEROUN: REQUÊTE - EXCEPTIONS PRÉLIMINAIRES - 28 ...
... si «les faits allégués par le demandeur» sont ou ... si le Cameroun était en droit,
à diverges dates après le dépôt de sa requête modifiée, de soumettre ...
www.lawschool.cornell.edu/library/cijwww/cijwww/cdocket/ cnc/cncapplication/cnc_capplication_981028.html - 31k

and Seconde Modification à l'Acte d'Accusation
LE PROCUREUR DU TRIBUNAL CONTRE. DUSKO TADIC alias "DULE" alias "DUSAN".
GORAN BOROVNICA. ACTE D'ACCUSATION (MODIFIÉ). Richard J. Goldstone ...
www.un.org/icty/indictment/french/tad-2ai951214f.htm - 30k