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An operational annotation is indicated by a two-character
operational annotation marker
(OPAM). The first character is a
plus sign and the second character is a letter.
OPAM annotations support formal construction of complex and
large molecules from small molecules, substituents,
structural repeat units (SRUs) and special entities such
as a peptide sequence. OPAMs and their usage are listed in the following table.
| OPAM |
Meaning and usage |
| +A |
addition of chemical species:
addition of chemical species, to be used in those cases where the
dot notation is not applicable, for example to add a species
with a non-integer coefficients such as a water molecule in a hemihydrate
|
| +C |
addition of a counterion:
an annotation of this type can occur at a charged atom to add
the notation of an oppositely charged ion
|
| +L |
ligand addition:
addition of monodentate and/or polydentate ligand molecules
to a central atom of a coordination complex
|
| +R |
alkyl group addition:
generic or specified addition of alkyl group;
specification of members of a homologous series
|
| +X |
halogen atom addition:
addition of F, Cl, Br, or I atom
|
| +Y |
any atom, group, or entity addition:
generic addition of a group; specification of a compound class
|
| +m |
additive repetitions to build a polymer:
generic polymer annotation used when the special cased +n and +r do not apply
|
| +n |
additive repetitions to build a regular single-strand polymer:
head-to-tail connection of SRUs via single bond
|
| +r |
additive repetition to build a ring:
formal generation of a macrocycle
|
| +s |
copolymer specification:
this annotation is anchored at the tail node of the last
(right-most) SRU in a SRU sequence to provide copolymer details
|
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