paleonet question marks in taxonomic names

[björn kröger <bjoekroe@xxxxxx>]

Dear colleagues,

when the status of a taxon, or the taxonomic position of a specimen  
is not clear in some taxonomic papers the taxa contain question marks  
at different positions, such as:

?Michelinoceras michelini (Barrande, 1866)
Michelinoceras? michelini (Barrande, 1866)
Michelinoceras ?michelini (Barrande, 1866)
Michelinoceras michelini? (Barrande, 1866)

I guess, every position has a different meaning and the position is  
regulated by a rule of the ICZN.
However, where can I find this rule and where is written what the the  
meaning of each specific position of the question mark is?

Any information is appreciated

Bjoern



----------------------
Dr. Björn Kröger
Museum für Naturkunde
an der Humboldt Universität Berlin
Invalidenstr. 43
D-10115 Berlin
Germany