The Special Anniversary Edition appeared in 1999 to mark 75 years of the Meisterstück and was made in that one year only. Compared with the standard model it had a specially designed nib, an additional ring on the cap and more elaborate packaging; a CD came with it. The premium was modest, around 20 euros at the time. So it really is a Special Edition and not a relabelled standard model.
To be distinguished from this are the 145s that Montblanc has repeatedly sold with something thrown in, sometimes a Chopin recording, sometimes a CD by Plácido Domingo or Lang Lang. These are ordinary production pens; the extra served to boost sales and does not turn the pen into a special edition. The names Chopin and Mozart likewise stand not for editions but for sizes: Chopin means the 145, Mozart the smaller Meisterstück models.
A Special Edition and a Limited Edition are two different things. A Special Edition is limited only in time; how many were made remains unknown. A Limited Edition is limited in number, and the size of the run appears on the pen itself, in a form such as 0123/1924. Where such numbering is absent, it is not a Limited Edition, whatever the box or the sales blurb may imply.