2. The computer-implemented method of claim 1 , further comprising: receiving a statement that requires that a particular operation be performed on content stored within a certain subdocument of said plurality of subdocuments; and based on one or more compound document declarations that are stored separate from the plurality of compound documents, making a determination that said particular operation is not permitted.
2. The computer-implemented method of claim 1 , further comprising: receiving a statement that requires that a particular operation be performed on content stored within a certain subdocument of said plurality of subdocuments; and based on one or more compound document declarations that are stored separate from the plurality of compound documents, making a determination that said particular operation is not permitted. 3. The computer-implemented method of claim 2 , wherein: one of the one or more compound document declarations specifies an error message; and the method further comprising displaying said error message in response to making said determination.