Index - I
| Identifier | Language.ATS |
| IdentifierSpace | Language.ATS |
| If | Language.ATS |
| IfCase | Language.ATS |
| Impl | Language.ATS |
| Implement | Language.ATS |
| Implementation | Language.ATS |
| ImplicitType | Language.ATS |
| Include | Language.ATS |
| Index | Language.ATS |
| Infix | Language.ATS |
| IntLit | Language.ATS |
| IntTok | Language.ATS |