1. A computer-implemented method of copying a document and its associated metadata, the method comprising: receiving a document that includes pages; generating, with one or more processors, page metadata for each page of the document and document metadata for the document; receiving a modification of a first page in the document; updating, with the one or more processors, the page metadata for the first page; generating, with the one or more processors, a hash of the modification in the document metadata; receiving a first request for a first copy of the document; copying the document, the page metadata and the document metadata; and transmitting the document, the page metadata and the document metadata based on the first request.
1. A computer-implemented method of copying a document and its associated metadata, the method comprising: receiving a document that includes pages; generating, with one or more processors, page metadata for each page of the document and document metadata for the document; receiving a modification of a first page in the document; updating, with the one or more processors, the page metadata for the first page; generating, with the one or more processors, a hash of the modification in the document metadata; receiving a first request for a first copy of the document; copying the document, the page metadata and the document metadata; and transmitting the document, the page metadata and the document metadata based on the first request. 2. The method of claim 1 , further comprising the steps of: receiving a notification of an erasure of at least one segment of a stroke; removing the at least one segment from the page metadata associated with the page where the stroke appears; and removing the at least one segment from the document metadata.