A Class A.
B Class B.
C Exempt from Nasdaq listing requirements for a limited period of time.
D A new issue of an existing stock. (Often the result of a reverse split.)
E Delinquent in required filings with the SEC as determined by the NASD.
G First Convertible Bond.
H Second Convertible Bond, same company.
I Third Convertible Bond, same company.
L Miscellaneous situations such as foreign preferred, preferred when-issued, a second class of units, a third class of warrants, or a sixth class of preferred stock.
M Fourth preferred, same company.