The dot of augmentation (not division) is a performance option which is technically not an ornament, although it can be used as such. The dot is integral to the polyphonic web. It would be a mistake to assume that there is a correct version--different mss often show variations in dots and ties. Prints are often different from mss because printed the dots and ties was often too much bother. In sources that are undotted specifically owing to technical limitations of the source, it is reasonably to supply the dots from a concordance, keeping in mind that you may be creating a new, unique version, and that undotted performances are an option. In this sense, editions are still hamstrung (not gut strung) with the older idea of an urtext, that if you go back far enough, you will see a perfect, correct score. What happens when you go back to earlier sources is that you see, understandably, earlier versions. The best you can do is find a fairly accurate copyist, which does not really signify either correctness, "ur-ness" or intent.
So you may dot and tie as you please, hopefully within the bounds of style, keeping in mind that you may introduce a parallel fifth or octave, or, more often, avoid one--this is one of the main uses of the dot, particularly for delayed fifths. So, in order to use, or not use, the dot, in polyphony you have to also be able to hear or see the parallels. If you grew up singing this music, you would hear them instantly, as quickly as spotting a beret on the Mona Lisa, but you would also have a strong sense of style so that notational shorthand would not be an issue. Extant exercise books, in which the successive intervals are marked with numbers, show exactly how the voice-leading was studied and checked as a part of basic music curriculum. A secondary use of the dot, which becomes more important from the mid-16th century on, is for ornamentation. There are some theories about mss dotting, cited by Lumsden, as to dating English early 17th c. mss by the number and style of dotting. In this narrower sense, this seems to be an indicator with exceptions. The dot means different things in different times and places, however, this is true for notation as a whole. dt To get on or off this list see list information at http://www.cs.dartmouth.edu/~wbc/lute-admin/index.html
