| UD | Language.Drasil.Chunk.UnitDefn, Language.Drasil |
| UDefn | Language.Drasil.UnitLang |
| udefn | Language.Drasil.Classes |
| UFunc | Language.Drasil.Expr.Lang, Language.Drasil.ModelExpr.Development, Language.Drasil.Expr.Development, Drasil.Code.CodeExpr.Development |
| UFuncB | Language.Drasil.Expr.Lang, Language.Drasil.ModelExpr.Development, Language.Drasil.Expr.Development, Drasil.Code.CodeExpr.Development |
| UFuncVN | Language.Drasil.Expr.Lang, Language.Drasil.ModelExpr.Development, Language.Drasil.Expr.Development, Drasil.Code.CodeExpr.Development |
| UFuncVV | Language.Drasil.Expr.Lang, Language.Drasil.ModelExpr.Development, Language.Drasil.Expr.Development, Drasil.Code.CodeExpr.Development |
| UlC | Language.Drasil.Document.Core, Language.Drasil.Document |
| ulcc | Language.Drasil.Document.Sections, Language.Drasil.Document |
| UnaryOp | |
| 1 (Data Constructor) | Language.Drasil.Expr.Lang, Language.Drasil.Expr.Development |
| 2 (Data Constructor) | Language.Drasil.ModelExpr.Lang, Language.Drasil.ModelExpr.Development |
| 3 (Data Constructor) | Drasil.Code.CodeExpr.Lang, Drasil.Code.CodeExpr.Development |
| UnaryOpB | |
| 1 (Data Constructor) | Language.Drasil.Expr.Lang, Language.Drasil.Expr.Development |
| 2 (Data Constructor) | Language.Drasil.ModelExpr.Lang, Language.Drasil.ModelExpr.Development |
| 3 (Data Constructor) | Drasil.Code.CodeExpr.Lang, Drasil.Code.CodeExpr.Development |
| UnaryOpVN | |
| 1 (Data Constructor) | Language.Drasil.Expr.Lang, Language.Drasil.Expr.Development |
| 2 (Data Constructor) | Language.Drasil.ModelExpr.Lang, Language.Drasil.ModelExpr.Development |
| 3 (Data Constructor) | Drasil.Code.CodeExpr.Lang, Drasil.Code.CodeExpr.Development |
| UnaryOpVV | |
| 1 (Data Constructor) | Language.Drasil.Expr.Lang, Language.Drasil.Expr.Development |
| 2 (Data Constructor) | Language.Drasil.ModelExpr.Lang, Language.Drasil.ModelExpr.Development |
| 3 (Data Constructor) | Drasil.Code.CodeExpr.Lang, Drasil.Code.CodeExpr.Development |
| unc | Language.Drasil.Uncertainty, Language.Drasil |
| uncert | Language.Drasil.Uncertainty |
| Uncertainty | Language.Drasil.Uncertainty, Language.Drasil |
| UncertQ | Language.Drasil.Chunk.UncertainQuantity, Language.Drasil |
| uncPrec | Language.Drasil.Uncertainty, Language.Drasil |
| uncty | Language.Drasil.Uncertainty, Language.Drasil |
| uncVal | Language.Drasil.Uncertainty, Language.Drasil |
| underConsidertn | Language.Drasil.Document.SentenceCombinators, Language.Drasil.Document |
| unicodeConv | Language.Drasil.Symbol.Helpers, Language.Drasil |
| unitCon | Language.Drasil.Chunk.UnitDefn, Language.Drasil |
| UnitDefn | Language.Drasil.Chunk.UnitDefn, Language.Drasil |
| UnitEq | Language.Drasil.Classes |
| uniteq | Language.Drasil.Classes |
| UnitSymbol | Language.Drasil.UnitLang |
| UnlabelledContent | Language.Drasil.Document.Core, Language.Drasil.Document |
| UnlblC | Language.Drasil.Document.Core, Language.Drasil.Document |
| unlbldCode | Language.Drasil.Document.Contents, Language.Drasil.Document |
| unlbldExpr | Language.Drasil.Document.Contents, Language.Drasil.Document |
| Unpublished | Language.Drasil.Data.Citation, Language.Drasil |
| unwrap | Language.Drasil.Document.SentenceCombinators, Language.Drasil.Document |
| UpFrom | Language.Drasil.Space, Language.Drasil |
| Upper | Language.Drasil.Sentence.Fold, Language.Drasil |
| upperLeft | Language.Drasil.Symbol.Helpers, Language.Drasil |
| UpTo | Language.Drasil.Space, Language.Drasil |
| uq | Language.Drasil.Chunk.UncertainQuantity, Language.Drasil |
| uqc | Language.Drasil.Chunk.UncertainQuantity, Language.Drasil |
| uqcND | Language.Drasil.Chunk.UncertainQuantity, Language.Drasil |
| uqDirect | Language.Drasil.Chunk.UncertainQuantity, Language.Drasil |
| URI | Language.Drasil.Label.Type, Language.Drasil |
| URL | Language.Drasil.Data.Citation, Language.Drasil |
| US | Language.Drasil.UnitLang, Language.Drasil |
| UScale | Language.Drasil.UnitLang |
| UShift | Language.Drasil.UnitLang |
| USymb | Language.Drasil.UnitLang, Language.Drasil |
| usymb | Language.Drasil.Classes, Language.Drasil |
| USynonym | Language.Drasil.UnitLang |