1. A method implemented on a client computer, for merging document metadata at a client computer, the method comprising: obtaining, by the client computer, a document from a server computer at the client computer, the document being requested by a user at the client computer; opening the document at the client computer; in response to opening the document at the client computer, determining, by the client computer, whether the document includes unit identifiers, the unit identifiers including one or more paragraph identifiers, sentence identifiers or table identifiers; when a determination is made that the document does not include paragraph identifiers, assigning a paragraph identifier to each paragraph in the document; receiving a first message from the server computer providing notification that at least one other user is authoring the document; in response to receiving the first message from the server computer that at least one other user is authoring the document, sending a second message to the server computer, the second message including first metadata for the document, the first metadata including a first next paragraph identifier for the document, a first document identifier and a first revision identifier; determining a first paragraph identifier range from the first document identifier and from the first next paragraph identifier, a first identifier in the first paragraph identifier range being the first document identifier and a last identifier in the first paragraph identifier range being one less than the first next paragraph identifier; in response to sending the second message to the server computer, receiving a third message from the server computer, the third message including second metadata for the document, the second metadata including a second next paragraph identifier for the document, a second document identifier and a second revision identifier; determining a second paragraph identifier range from the second document identifier and from the second next paragraph identifier, a first identifier in the second paragraph identifier range being the second document identifier and a last identifier in the second paragraph identifier range being one less than the second next paragraph identifier; in response to receiving the third message from the server computer, determining whether the first metadata and the second metadata should be merged by: determining whether the first revision identifier matches the second revision identifier; when a determination is made that the first revision identifier matches the second revision identifier, determining whether the first document identifier matches the second document identifier; when a determination is made that the first revision identifier matches the second revision identifier and when a determination is made that the first document identifier does not match the second document identifier, determining whether a size of the first paragraph identifier range matches a size of the second paragraph identifier range; and when a determination is made that the first revision identifier matches the second revision identifier, when a determination is made that the first document identifier does not match the second document identifier and when a determination is made that the size of the first paragraph identifier range matches the size of the second paragraph identifier range, determining that the first metadata and the second metadata should be merged; and when a determination is made that the first metadata and the second metadata should be merged, adjusting paragraph identifiers in the document based on the second metadata.