A computer system includes a repository with predefined data elements for use in identifying information portions in electronic communications. Each data element is associated with semantic information indicating its definition and intended use. The system includes a modeling tool that, upon selection by a user, displays any of the predefined data elements and the semantic information for editing. A method includes receiving a first user input made under guidance of the modeling tool in a graphical user interface (GUI). The input selects one of several predefined data elements that are associated with semantic information indicating their definition and intended use. In response to the first user input, a representation of the selected predefined data element containing the semantic information is presented in the GUI. At least one aspect of the semantic information is modified based on a second user input made under guidance of the modeling tool.