10. A method for enabling in-context authoring of substitute content for one or more non-textual objects, comprising: accessing an electronic document including content data that includes sentences and at least one non-textual object contextually placed in a first position within the sentences; and presenting substitute content positioned in the first position within the sentences, wherein the substitute content corresponds to the at least one non-textual object; presenting at least a portion of the sentences positioned adjacent to the first position to enable a user to contextually review the substitute content with respect to the sentences; editing the substitute content positioned in the first position within the sentences and in response to editing commands; and storing the substitute content in the electronic document.
10. A method for enabling in-context authoring of substitute content for one or more non-textual objects, comprising: accessing an electronic document including content data that includes sentences and at least one non-textual object contextually placed in a first position within the sentences; and presenting substitute content positioned in the first position within the sentences, wherein the substitute content corresponds to the at least one non-textual object; presenting at least a portion of the sentences positioned adjacent to the first position to enable a user to contextually review the substitute content with respect to the sentences; editing the substitute content positioned in the first position within the sentences and in response to editing commands; and storing the substitute content in the electronic document. 14. A method according to claim 10 , wherein the non-textual object is selected from the group comprising graphics, images, icons, controls, applications, audio output, video output, tactile output, MathML, SMIL and subdocuments.