Repeating single CHEM monomer is incorrectly invalid

[ClairePA]

Single monomers with brackets are valid and accepted by the webeditor.

PEPTIDE1{A'11'}$$$$V2.0

but I draw the following

the correct HELM is generated CHEM1{[Az]'11'}$$$$V2.0 and the HELM a molecule properties are calculated.

However, if I clear the editor and paste in the HELM string CHEM1{[Az]'11'}$$$$V2.0 and click Apply, only one monomer is displayed: and the HELM string is changed to CHEM1{[Az]}$$$$V2.0

The webservices state that CHEM1{[Az]'11'}$$$$V2.0 is invalid HELM.

[MarkusWeisser]

Repeating units cannot be used with CHEM monomers, only with RNA or PEPTIDE monomers. The reason for that is that CHEM monomers have not a defined connection order (R1 goes to R2) for automatically creating polymers. This should be mentioned in the HELM specification and the Editor should show the parser error.

[ClairePA]

Thanks Markus - you are completely right.

I have updated the spec. The issue about the editor showing the parser error is wider than just this issue and will be taken up elsewhere.