A method for processing a portion of a computer document in a computer system, the content of the computer document being represented by a markup language, each tag of which having a name and a value, the computer document being associated with a second computer document, referred to as a "schema document", the content of which is represented in a schema type markup language, the schema document defining the structure of the portion under consideration of the computer document. This processing method comprises the steps of: selection (S13) of a tag, referred to as the "current tag", in the portion of the computer document; searching (S15-S21) in the schema document for at least one declarative tag of a function associated with the selected tag of the computer document; creation (S23, S25) of a list of functions applicable to the current tag of the computer document from at least one declarative tag of a function, found in the schema document.