In this article the list of labels that are used in the Proposal Portal are shown. The name in the list can be used as a search criterium to find and override the correct label (via Salesforce Setup - Build - Create - Custom Labels). This is needed when overriding fields in the portal (please view this article for more information about overriding fields in the proposal portal).
The labels that are only used in the Proposal portal and can therefore be overridden without problems:
The following labels are not exclusive to the Proposal portal and are thus also used in other places in Salesforce. Please be careful with these labels and not just change these without thorough consideration: