Markup block - Gen<None> - 22 - (0:0,0)
    Markup span - Gen<Markup> - [] - SpanEditHandler;Accepts:Any - (0:0,0) - Tokens:1
        SyntaxKind.Unknown;[];
    Directive block - Gen<Directive:{custom;SingleLine;Unrestricted}> - 22 - (0:0,0)
        Transition span - Gen<None> - [@] - SpanEditHandler;Accepts:None - (0:0,0) - Tokens:1
            SyntaxKind.Transition;[@];
        MetaCode span - Gen<None> - [custom] - SpanEditHandler;Accepts:None - (1:0,1) - Tokens:1
            SyntaxKind.Identifier;[custom];
        Markup span - Gen<None> - [ ] - SpanEditHandler;Accepts:Whitespace - (7:0,7) - Tokens:1
            SyntaxKind.Whitespace;[ ];
        Code span - Gen<DirectiveToken {;String;Opt:True}> - ["simple-value"] - DirectiveTokenEditHandler;Accepts:NonWhitespace - (8:0,8) - Tokens:1
            SyntaxKind.StringLiteral;["simple-value"];
    Markup span - Gen<Markup> - [] - SpanEditHandler;Accepts:Any - (22:0,22) - Tokens:1
        SyntaxKind.Unknown;[];
