Enumerations for _Peak_char.Coupling_pattern (An open enumeration) 
d doublet 
dd 'doublet of doublets' 
ddd 'doublet of doublets of doublets' 
dm 'doublet of multiplets' 
dt 'doublet of triplets' 
hpt heptet 
hxt hextet 
m multiplet 
q quartet 
qd 'quartet of doublets' 
qn quintet 
s singlet 
sxt sextet 
t triplet 
td 'triplet of doublets'