A system, comprising: means for storing a document as a plurality of logical parts; means for establishing a document configuration when a digital signature of a signing user is applied to the document, wherein the means for establishing defines which of the plurality of logical parts are signed with the digital signature; means for indicating whether the document configuration is subsequently altered; and means for applying the signature to the parts, the plurality of logical parts includes a fixed document part, a core properties part, which is left unsigned; a digital signature definitions part which allows the signing user to define another user to additionally sign the document and to define conditions associated with the signature of the other user, and a package relationship part, wherein the package relationship part contains a link to the core properties part so a subsequent user can change the core properties without invalidating the signing user's signature and wherein signing the package relationship part prevents a subsequent user from changing the link without invalidating the signing user's digital signature; and the means for establishing comprises a digital signing policy rule which allows the other user to add document content and a signature of the other user to the document without invalidating the signing user's signature in accordance with said signing user's definition in the digital signature definitions part. means for storing a document as a plurality of logical parts; means for establishing a document configuration when a digital signature of a signing user is applied to the document, wherein the means for establishing defines which of the plurality of logical parts are signed with the digital signature; means for indicating whether the document configuration is subsequently altered; and means for applying the signature to the parts, the plurality of logical parts includes a fixed document part, a core properties part, which is left unsigned; a digital signature definitions part which allows the signing user to define another user to additionally sign the document and to define conditions associated with the signature of the other user, and a package relationship part, wherein the package relationship part contains a link to the core properties part so a subsequent user can change the core properties without invalidating the signing user's signature and wherein signing the package relationship part prevents a subsequent user from changing the link without invalidating the signing user's digital signature; and a fixed document part, a core properties part, which is left unsigned; a digital signature definitions part which allows the signing user to define another user to additionally sign the document and to define conditions associated with the signature of the other user, and a package relationship part, wherein the package relationship part contains a link to the core properties part so a subsequent user can change the core properties without invalidating the signing user's signature and wherein signing the package relationship part prevents a subsequent user from changing the link without invalidating the signing user's digital signature; and the means for establishing comprises a digital signing policy rule which allows the other user to add document content and a signature of the other user to the document without invalidating the signing user's signature in accordance with said signing user's definition in the digital signature definitions part.