Methods and systems for annotating electronic documents

A computer-implemented method of comparing electronic documents comprising:

• creating a first document signature of a first electronic document file;
• creating a second document signature of a second electronic document file;
• comparing the first document signature to the second document signature to generate a document similarity value;
• and
• comparing, by a computer device, the document similarity value to a threshold similarity value, wherein the first and second electronic document files are compatible documents if the document similarity value is greater than the threshold similarity value.

A computer-implemented method of annotating an electronic document comprising:

• receiving annotation information corresponding to an annotation of a first electronic document file at an annotation location;
• generating annotation metadata associated with the annotation information by creating topographic patterns corresponding to the first electronic document file and the annotation information, wherein the topographic patterns include one or more document patterns, one or more anchor patterns, one or more neighborhood patterns, or combinations thereof;
• storing the annotation information and associated annotation metadata in an annotation file that is separate from the first electronic document file;
• generating topographic patterns corresponding to a target electronic document file, wherein the topographic patterns include document patterns, anchor patterns, neighborhood patterns, or combinations thereof;
• comparing the topographic patterns of the first electronic document file to the topographic patterns of the target electronic document file to determine an anchor location within the target electronic document file;
• and
• anchoring the annotation information, by a computer device, to the target electronic document file.