| Architecture | Description | Class | n° Families | Structure |
|---|---|---|---|---|
| 2H | RNAs with two hairpin substructures | structured_simple | 543 | |
| 3H | RNAs with three hairpin substructures | structured_simple | 121 | |
| 3WJ | RNAs with three way junction | structured_simple | 173 | |
| 4H | RNAs with four hairpin substructures | structured_simple | 55 | |
| 4WJ | RNAs with four way junction | structured_simple | 47 | |
| complex unclassified | Complex RNAs with no known distinct domain | structured_complex | 277 | |
| hairpin | RNAs with single hairpin | structured_simple | 1309 | |
| Intron_gpI-like | RNAs structured similarly to Group I introns | structured_complex | 5 | |
| Intron_gpII-like | RNAs structured similarly to Group II introns | structured_complex | 12 | |
| IRES_multi_domain | RNAs with Internal Ribosome Entry Sites and other domains | structured_complex | 28 | |
| multiple_domains | RNAs with multiple and/or various domains | structured_complex | 22 | |
| pseudoknot_simple | RNAs with simple pseudoknot | structured_simple | 41 | |
| RNaseP | Ribonuclease P structures | structured_complex | 7 | |
| rRNA | Ribosomal RNAs | structured_complex | 14 | |
| SRP | Signal recognition RNAs | structured_complex | 8 | |
| telomerase | Telomerase RNA components | structured_complex | 4 | |
| tRNA-like | RNAs structurally resembling tRNAs | structured_simple | 15 | |
| U1_snRNA | U1 spliceosomal small nuclear RNAs | structured_complex | 4 | |
| U4_snRNA | U4 spliceosomal small nuclear RNAs | structured_complex | 3 |