The PetrArchive is a new digital archive and â€°Ã›Ãrich textâ€°Ã›Â edition of Francesco Petrarca's iconic fourteenth-century songbook Rerum vulgarium fragmenta (Rvf; Canzoniere). A primary goal of the PetrArchive is to document, investigate and illustrate the graphic codes and structuresâ€°Ã›Ã“especially the â€°Ã›Ãvisual poeticsâ€°Ã›Ââ€°Ã›Ã“of the work. Our paper will discuss and demonstrate specifically the broad issue of indexicality in the context of the digital editing and encoding practices and strategies adopted and exploited in pursuit of this goal. The Rvf is both in its manuscript tradition and our new edition a highly indexed and indexable book. An index often contains a list of words, subjects, titles and addresses, as well as pointers and locations of references. These lists and addresses provide a representation, map, or model of a document. A comprehensive, hierarchical, multifaceted index to, for instance, a large edition of letters is of tremendous practical value as a guide through the collection. An index may also be a remarkable work in itself as a structured conceptual model of the contents of a collection. Often indexical structures are embedded in the document as we find in the Bible and other religious texts, with book titles, chapter and verse numbers, and cross-references embedded throughout the text. Petrarch's adherence in his model holograph MS Vatican Latino 3195 to his 31-line graphic canvas and his designs of various combinations of verse forms to fill that canvas generate, among other things, a visual index to the document, with the textual and graphic shapes of the manuscript serving as a visual map of genre and generic juxtaposition. Our project will build a graphic representation, or visualization, of the manuscript that will allow readers to browse and scanâ€°Ã›Ã“by shape and structureâ€°Ã›Ã“the distribution, combination, and juxtaposition of genre and form throughout the manuscript. Another aspect of our visual and schematic indices to the edition will be the animation of Petrarch's own poetics of erasure and transcription, through which he revises his texts but also deforms the patterns of his own indexical practices to highlight the importance of the work's visual-poetic structuring. We will demonstrate an example of this deformation in our animation of the canzone Quel' antiquo mio dolce empio signore (Rvf 360). In his own holograph MS, by then a service copy, Petrarch is forced to abandon his ideal layout for the prosodic form of the canzone. Only in subsequent MSS will the canzone revert to its ideal, authorial form not in the author's hand. Our representation will allow readers to view the poem morphing from one layout to the other, requiring the encoding of both the actual and ideal layout in the document and the interpretation of those codes in the digital design and publishing layers of the edition. Beyond their instant utility in allowing users an overview of the design of individual MS pages and of the Rvf's complex system of combining forms, these indices reconfigure the equally complex layers of indexical structures inherent in a scholarly edition.