| Allowed Value | Details | 
|---|---|
| 2'-5'-phosphodiester linkage | |
| base modification | |
| cyclic nucleotide | |
| phosphate modification | |
| sugar modification | 
| Allowed Value | Details | 
|---|---|
| 2'-5'-phosphodiester linkage | |
| base modification | |
| cyclic nucleotide | |
| phosphate modification | |
| sugar modification |