Can you abbreviate the title of the Proceeedings of the IEEE? I found this on Page 34 of IEEE EDITORIAL STYLE MANUAL, it's about how to edit the reference. I don't understand the following sentence: 


  NOTE: The only exception to this rule is PROCEEDINGS OF THE IEEE, which never carried an acronym on the masthead


Does it mean when cite a paper from PROCEEDINGS OF THE IEEE, do not cite it in an abbreviation form. If it is, why the following example ( Page 35 of IEEE EDITORIAL STYLE MANUAL) gave an abbreviation form:
The part you quote does not refer to the name of the Journal but to the vol. ##, no. ## section of the citation and is applicable to those earlier than 1988. 

So the 1981 citation would be 


IEEE Trans. Automat. Contr., vol. AC-26, no.1, pp. 1–34, Jan. 1981.


while a citation from the same journal past 1988 would be


IEEE Trans. Automat. Contr., vol. 40, no.1, pp. 1–34, Jan. 1995.


The exception to the Proc. of IEEE applies here, as it never had an abbreviation in the volume and it has always been:


Proc. IEEE, vol. 11, no. 3, pp. 1-11, Jan. 1978.


The example they provide is correct.