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+(* $Id$ *)
+
+theory Outer_Syntax
+imports Pure
+begin
+
+chapter {* Syntax primitives *}
+
+text {*
+  The rather generic framework of Isabelle/Isar syntax emerges from
+  three main syntactic categories: \emph{commands} of the top-level
+  Isar engine (covering theory and proof elements), \emph{methods} for
+  general goal refinements (analogous to traditional ``tactics''), and
+  \emph{attributes} for operations on facts (within a certain
+  context).  Subsequently we give a reference of basic syntactic
+  entities underlying Isabelle/Isar syntax in a bottom-up manner.
+  Concrete theory and proof language elements will be introduced later
+  on.
+
+  \medskip In order to get started with writing well-formed
+  Isabelle/Isar documents, the most important aspect to be noted is
+  the difference of \emph{inner} versus \emph{outer} syntax.  Inner
+  syntax is that of Isabelle types and terms of the logic, while outer
+  syntax is that of Isabelle/Isar theory sources (specifications and
+  proofs).  As a general rule, inner syntax entities may occur only as
+  \emph{atomic entities} within outer syntax.  For example, the string
+  @{verbatim "\"x + y\""} and identifier @{verbatim z} are legal term
+  specifications within a theory, while @{verbatim "x + y"} without
+  quotes is not.
+
+  Printed theory documents usually omit quotes to gain readability
+  (this is a matter of {\LaTeX} macro setup, say via @{verbatim
+  "\\isabellestyle"}, see also \cite{isabelle-sys}).  Experienced
+  users of Isabelle/Isar may easily reconstruct the lost technical
+  information, while mere readers need not care about quotes at all.
+
+  \medskip Isabelle/Isar input may contain any number of input
+  termination characters ``@{verbatim ";"}'' (semicolon) to separate
+  commands explicitly.  This is particularly useful in interactive
+  shell sessions to make clear where the current command is intended
+  to end.  Otherwise, the interpreter loop will continue to issue a
+  secondary prompt ``@{verbatim "#"}'' until an end-of-command is
+  clearly recognized from the input syntax, e.g.\ encounter of the
+  next command keyword.
+
+  More advanced interfaces such as Proof~General \cite{proofgeneral}
+  do not require explicit semicolons, the amount of input text is
+  determined automatically by inspecting the present content of the
+  Emacs text buffer.  In the printed presentation of Isabelle/Isar
+  documents semicolons are omitted altogether for readability.
+
+  \begin{warn}
+    Proof~General requires certain syntax classification tables in
+    order to achieve properly synchronized interaction with the
+    Isabelle/Isar process.  These tables need to be consistent with
+    the Isabelle version and particular logic image to be used in a
+    running session (common object-logics may well change the outer
+    syntax).  The standard setup should work correctly with any of the
+    ``official'' logic images derived from Isabelle/HOL (including
+    HOLCF etc.).  Users of alternative logics may need to tell
+    Proof~General explicitly, e.g.\ by giving an option @{verbatim "-k ZF"}
+    (in conjunction with @{verbatim "-l ZF"}, to specify the default
+    logic image).  Note that option @{verbatim "-L"} does both
+    of this at the same time.
+  \end{warn}
+*}
+
+
+section {* Lexical matters \label{sec:lex-syntax} *}
+
+text {*
+  The Isabelle/Isar outer syntax provides token classes as presented
+  below; most of these coincide with the inner lexical syntax as
+  presented in \cite{isabelle-ref}.
+
+  \begin{matharray}{rcl}
+    @{syntax_def ident} & = & letter\,quasiletter^* \\
+    @{syntax_def longident} & = & ident (\verb,.,ident)^+ \\
+    @{syntax_def symident} & = & sym^+ ~|~ \verb,\,\verb,<,ident\verb,>, \\
+    @{syntax_def nat} & = & digit^+ \\
+    @{syntax_def var} & = & ident ~|~ \verb,?,ident ~|~ \verb,?,ident\verb,.,nat \\
+    @{syntax_def typefree} & = & \verb,',ident \\
+    @{syntax_def typevar} & = & typefree ~|~ \verb,?,typefree ~|~ \verb,?,typefree\verb,.,nat \\
+    @{syntax_def string} & = & \verb,", ~\dots~ \verb,", \\
+    @{syntax_def altstring} & = & \backquote ~\dots~ \backquote \\
+    @{syntax_def verbatim} & = & \verb,{*, ~\dots~ \verb,*,\verb,}, \\[1ex]
+
+    letter & = & latin ~|~ \verb,\,\verb,<,latin\verb,>, ~|~ \verb,\,\verb,<,latin\,latin\verb,>, ~|~ greek ~|~ \\
+           &   & \verb,\<^isub>, ~|~ \verb,\<^isup>, \\
+    quasiletter & = & letter ~|~ digit ~|~ \verb,_, ~|~ \verb,', \\
+    latin & = & \verb,a, ~|~ \dots ~|~ \verb,z, ~|~ \verb,A, ~|~ \dots ~|~ \verb,Z, \\
+    digit & = & \verb,0, ~|~ \dots ~|~ \verb,9, \\
+    sym & = & \verb,!, ~|~ \verb,#, ~|~ \verb,$, ~|~ \verb,%, ~|~ \verb,&, ~|~
+     \verb,*, ~|~ \verb,+, ~|~ \verb,-, ~|~ \verb,/, ~|~ \\
+    & & \verb,<, ~|~ \verb,=, ~|~ \verb,>, ~|~ \verb,?, ~|~ \texttt{\at} ~|~
+    \verb,^, ~|~ \verb,_, ~|~ \verb,|, ~|~ \verb,~, \\
+    greek & = & \verb,\<alpha>, ~|~ \verb,\<beta>, ~|~ \verb,\<gamma>, ~|~ \verb,\<delta>, ~| \\
+          &   & \verb,\<epsilon>, ~|~ \verb,\<zeta>, ~|~ \verb,\<eta>, ~|~ \verb,\<theta>, ~| \\
+          &   & \verb,\<iota>, ~|~ \verb,\<kappa>, ~|~ \verb,\<mu>, ~|~ \verb,\<nu>, ~| \\
+          &   & \verb,\<xi>, ~|~ \verb,\<pi>, ~|~ \verb,\<rho>, ~|~ \verb,\<sigma>, ~|~ \verb,\<tau>, ~| \\
+          &   & \verb,\<upsilon>, ~|~ \verb,\<phi>, ~|~ \verb,\<chi>, ~|~ \verb,\<psi>, ~| \\
+          &   & \verb,\<omega>, ~|~ \verb,\<Gamma>, ~|~ \verb,\<Delta>, ~|~ \verb,\<Theta>, ~| \\
+          &   & \verb,\<Lambda>, ~|~ \verb,\<Xi>, ~|~ \verb,\<Pi>, ~|~ \verb,\<Sigma>, ~| \\
+          &   & \verb,\<Upsilon>, ~|~ \verb,\<Phi>, ~|~ \verb,\<Psi>, ~|~ \verb,\<Omega>, \\
+  \end{matharray}
+
+  The syntax of @{syntax string} admits any characters, including
+  newlines; ``@{verbatim "\""}'' (double-quote) and ``@{verbatim
+  "\\"}'' (backslash) need to be escaped by a backslash; arbitrary
+  character codes may be specified as ``@{verbatim "\\"}@{text ddd}'',
+  with three decimal digits.  Alternative strings according to
+  @{syntax altstring} are analogous, using single back-quotes instead.
+  The body of @{syntax verbatim} may consist of any text not
+  containing ``@{verbatim "*"}@{verbatim "}"}''; this allows
+  convenient inclusion of quotes without further escapes.  The greek
+  letters do \emph{not} include @{verbatim "\<lambda>"}, which is already used
+  differently in the meta-logic.
+
+  Common mathematical symbols such as @{text \<forall>} are represented in
+  Isabelle as @{verbatim \<forall>}.  There are infinitely many Isabelle
+  symbols like this, although proper presentation is left to front-end
+  tools such as {\LaTeX} or Proof~General with the X-Symbol package.
+  A list of standard Isabelle symbols that work well with these tools
+  is given in \cite[appendix~A]{isabelle-sys}.
+  
+  Source comments take the form @{verbatim "(*"}~@{text
+  "\<dots>"}~@{verbatim "*)"} and may be nested, although user-interface
+  tools might prevent this.  Note that this form indicates source
+  comments only, which are stripped after lexical analysis of the
+  input.  The Isar document syntax also provides formal comments that
+  are considered as part of the text (see \secref{sec:comments}).
+*}
+
+
+section {* Common syntax entities *}
+
+text {*
+  We now introduce several basic syntactic entities, such as names,
+  terms, and theorem specifications, which are factored out of the
+  actual Isar language elements to be described later.
+*}
+
+
+subsection {* Names *}
+
+text {*
+  Entity \railqtok{name} usually refers to any name of types,
+  constants, theorems etc.\ that are to be \emph{declared} or
+  \emph{defined} (so qualified identifiers are excluded here).  Quoted
+  strings provide an escape for non-identifier names or those ruled
+  out by outer syntax keywords (e.g.\ quoted @{verbatim "\"let\""}).
+  Already existing objects are usually referenced by
+  \railqtok{nameref}.
+
+  \indexoutertoken{name}\indexoutertoken{parname}\indexoutertoken{nameref}
+  \indexoutertoken{int}
+  \begin{rail}
+    name: ident | symident | string | nat
+    ;
+    parname: '(' name ')'
+    ;
+    nameref: name | longident
+    ;
+    int: nat | '-' nat
+    ;
+  \end{rail}
+*}
+
+
+subsection {* Comments \label{sec:comments} *}
+
+text {*
+  Large chunks of plain \railqtok{text} are usually given
+  \railtok{verbatim}, i.e.\ enclosed in @{verbatim "{"}@{verbatim
+  "*"}~@{text "\<dots>"}~@{verbatim "*"}@{verbatim "}"}.  For convenience,
+  any of the smaller text units conforming to \railqtok{nameref} are
+  admitted as well.  A marginal \railnonterm{comment} is of the form
+  @{verbatim "--"} \railqtok{text}.  Any number of these may occur
+  within Isabelle/Isar commands.
+
+  \indexoutertoken{text}\indexouternonterm{comment}
+  \begin{rail}
+    text: verbatim | nameref
+    ;
+    comment: '--' text
+    ;
+  \end{rail}
+*}
+
+
+subsection {* Type classes, sorts and arities *}
+
+text {*
+  Classes are specified by plain names.  Sorts have a very simple
+  inner syntax, which is either a single class name @{text c} or a
+  list @{text "{c\<^sub>1, \<dots>, c\<^sub>n}"} referring to the
+  intersection of these classes.  The syntax of type arities is given
+  directly at the outer level.
+
+  \indexouternonterm{sort}\indexouternonterm{arity}
+  \indexouternonterm{classdecl}
+  \begin{rail}
+    classdecl: name (('<' | subseteq) (nameref + ','))?
+    ;
+    sort: nameref
+    ;
+    arity: ('(' (sort + ',') ')')? sort
+    ;
+  \end{rail}
+*}
+
+
+subsection {* Types and terms \label{sec:types-terms} *}
+
+text {*
+  The actual inner Isabelle syntax, that of types and terms of the
+  logic, is far too sophisticated in order to be modelled explicitly
+  at the outer theory level.  Basically, any such entity has to be
+  quoted to turn it into a single token (the parsing and type-checking
+  is performed internally later).  For convenience, a slightly more
+  liberal convention is adopted: quotes may be omitted for any type or
+  term that is already atomic at the outer level.  For example, one
+  may just write @{verbatim x} instead of quoted @{verbatim "\"x\""}.
+  Note that symbolic identifiers (e.g.\ @{verbatim "++"} or @{text
+  "\<forall>"} are available as well, provided these have not been superseded
+  by commands or other keywords already (such as @{verbatim "="} or
+  @{verbatim "+"}).
+
+  \indexoutertoken{type}\indexoutertoken{term}\indexoutertoken{prop}
+  \begin{rail}
+    type: nameref | typefree | typevar
+    ;
+    term: nameref | var
+    ;
+    prop: term
+    ;
+  \end{rail}
+
+  Positional instantiations are indicated by giving a sequence of
+  terms, or the placeholder ``@{text _}'' (underscore), which means to
+  skip a position.
+
+  \indexoutertoken{inst}\indexoutertoken{insts}
+  \begin{rail}
+    inst: underscore | term
+    ;
+    insts: (inst *)
+    ;
+  \end{rail}
+
+  Type declarations and definitions usually refer to
+  \railnonterm{typespec} on the left-hand side.  This models basic
+  type constructor application at the outer syntax level.  Note that
+  only plain postfix notation is available here, but no infixes.
+
+  \indexouternonterm{typespec}
+  \begin{rail}
+    typespec: (() | typefree | '(' ( typefree + ',' ) ')') name
+    ;
+  \end{rail}
+*}
+
+
+subsection {* Mixfix annotations *}
+
+text {*
+  Mixfix annotations specify concrete \emph{inner} syntax of Isabelle
+  types and terms.  Some commands such as @{command "types"} (see
+  \secref{sec:types-pure}) admit infixes only, while @{command
+  "consts"} (see \secref{sec:consts}) and @{command "syntax"} (see
+  \secref{sec:syn-trans}) support the full range of general mixfixes
+  and binders.
+
+  \indexouternonterm{infix}\indexouternonterm{mixfix}\indexouternonterm{structmixfix}
+  \begin{rail}
+    infix: '(' ('infix' | 'infixl' | 'infixr') string? nat ')'
+    ;
+    mixfix: infix | '(' string prios? nat? ')' | '(' 'binder' string prios? nat ')'
+    ;
+    structmixfix: mixfix | '(' 'structure' ')'
+    ;
+
+    prios: '[' (nat + ',') ']'
+    ;
+  \end{rail}
+
+  Here the \railtok{string} specifications refer to the actual mixfix
+  template (see also \cite{isabelle-ref}), which may include literal
+  text, spacing, blocks, and arguments (denoted by ``@{text _}''); the
+  special symbol ``@{verbatim "\<index>"}'' (printed as ``@{text "\<index>"}'')
+  represents an index argument that specifies an implicit structure
+  reference (see also \secref{sec:locale}).  Infix and binder
+  declarations provide common abbreviations for particular mixfix
+  declarations.  So in practice, mixfix templates mostly degenerate to
+  literal text for concrete syntax, such as ``@{verbatim "++"}'' for
+  an infix symbol, or ``@{verbatim "++"}@{text "\<index>"}'' for an infix of
+  an implicit structure.
+*}
+
+
+subsection {* Proof methods \label{sec:syn-meth} *}
+
+text {*
+  Proof methods are either basic ones, or expressions composed of
+  methods via ``@{verbatim ","}'' (sequential composition),
+  ``@{verbatim "|"}'' (alternative choices), ``@{verbatim "?"}'' 
+  (try), ``@{verbatim "+"}'' (repeat at least once), ``@{verbatim
+  "["}@{text n}@{verbatim "]"}'' (restriction to first @{text n}
+  sub-goals, with default @{text "n = 1"}).  In practice, proof
+  methods are usually just a comma separated list of
+  \railqtok{nameref}~\railnonterm{args} specifications.  Note that
+  parentheses may be dropped for single method specifications (with no
+  arguments).
+
+  \indexouternonterm{method}
+  \begin{rail}
+    method: (nameref | '(' methods ')') (() | '?' | '+' | '[' nat? ']')
+    ;
+    methods: (nameref args | method) + (',' | '|')
+    ;
+  \end{rail}
+
+  Proper Isar proof methods do \emph{not} admit arbitrary goal
+  addressing, but refer either to the first sub-goal or all sub-goals
+  uniformly.  The goal restriction operator ``@{text "[n]"}''
+  evaluates a method expression within a sandbox consisting of the
+  first @{text n} sub-goals (which need to exist).  For example, the
+  method ``@{text "simp_all[3]"}'' simplifies the first three
+  sub-goals, while ``@{text "(rule foo, simp_all)[]"}'' simplifies all
+  new goals that emerge from applying rule @{text "foo"} to the
+  originally first one.
+
+  Improper methods, notably tactic emulations, offer a separate
+  low-level goal addressing scheme as explicit argument to the
+  individual tactic being involved.  Here ``@{text "[!]"}'' refers to
+  all goals, and ``@{text "[n-]"}'' to all goals starting from @{text
+  "n"}.
+
+  \indexouternonterm{goalspec}
+  \begin{rail}
+    goalspec: '[' (nat '-' nat | nat '-' | nat | '!' ) ']'
+    ;
+  \end{rail}
+*}
+
+
+subsection {* Attributes and theorems \label{sec:syn-att} *}
+
+text {*
+  Attributes (and proof methods, see \secref{sec:syn-meth}) have their
+  own ``semi-inner'' syntax, in the sense that input conforming to
+  \railnonterm{args} below is parsed by the attribute a second time.
+  The attribute argument specifications may be any sequence of atomic
+  entities (identifiers, strings etc.), or properly bracketed argument
+  lists.  Below \railqtok{atom} refers to any atomic entity, including
+  any \railtok{keyword} conforming to \railtok{symident}.
+
+  \indexoutertoken{atom}\indexouternonterm{args}\indexouternonterm{attributes}
+  \begin{rail}
+    atom: nameref | typefree | typevar | var | nat | keyword
+    ;
+    arg: atom | '(' args ')' | '[' args ']'
+    ;
+    args: arg *
+    ;
+    attributes: '[' (nameref args * ',') ']'
+    ;
+  \end{rail}
+
+  Theorem specifications come in several flavors:
+  \railnonterm{axmdecl} and \railnonterm{thmdecl} usually refer to
+  axioms, assumptions or results of goal statements, while
+  \railnonterm{thmdef} collects lists of existing theorems.  Existing
+  theorems are given by \railnonterm{thmref} and
+  \railnonterm{thmrefs}, the former requires an actual singleton
+  result.
+
+  There are three forms of theorem references:
+  \begin{enumerate}
+  
+  \item named facts @{text "a"},
+
+  \item selections from named facts @{text "a(i)"} or @{text "a(j - k)"},
+
+  \item literal fact propositions using @{syntax_ref altstring} syntax
+  @{verbatim "`"}@{text "\<phi>"}@{verbatim "`"} (see also method
+  @{method_ref fact} in \secref{sec:pure-meth-att}).
+
+  \end{enumerate}
+
+  Any kind of theorem specification may include lists of attributes
+  both on the left and right hand sides; attributes are applied to any
+  immediately preceding fact.  If names are omitted, the theorems are
+  not stored within the theorem database of the theory or proof
+  context, but any given attributes are applied nonetheless.
+
+  An extra pair of brackets around attributes (like ``@{text
+  "[[simproc a]]"}'') abbreviates a theorem reference involving an
+  internal dummy fact, which will be ignored later on.  So only the
+  effect of the attribute on the background context will persist.
+  This form of in-place declarations is particularly useful with
+  commands like @{command "declare"} and @{command "using"}.
+
+  \indexouternonterm{axmdecl}\indexouternonterm{thmdecl}
+  \indexouternonterm{thmdef}\indexouternonterm{thmref}
+  \indexouternonterm{thmrefs}\indexouternonterm{selection}
+  \begin{rail}
+    axmdecl: name attributes? ':'
+    ;
+    thmdecl: thmbind ':'
+    ;
+    thmdef: thmbind '='
+    ;
+    thmref: (nameref selection? | altstring) attributes? | '[' attributes ']'
+    ;
+    thmrefs: thmref +
+    ;
+
+    thmbind: name attributes | name | attributes
+    ;
+    selection: '(' ((nat | nat '-' nat?) + ',') ')'
+    ;
+  \end{rail}
+*}
+
+
+subsection {* Term patterns and declarations \label{sec:term-decls} *}
+
+text {*
+  Wherever explicit propositions (or term fragments) occur in a proof
+  text, casual binding of schematic term variables may be given
+  specified via patterns of the form ``@{text "(\<IS> p\<^sub>1 \<dots>
+  p\<^sub>n)"}''.  This works both for \railqtok{term} and \railqtok{prop}.
+
+  \indexouternonterm{termpat}\indexouternonterm{proppat}
+  \begin{rail}
+    termpat: '(' ('is' term +) ')'
+    ;
+    proppat: '(' ('is' prop +) ')'
+    ;
+  \end{rail}
+
+  \medskip Declarations of local variables @{text "x :: \<tau>"} and
+  logical propositions @{text "a : \<phi>"} represent different views on
+  the same principle of introducing a local scope.  In practice, one
+  may usually omit the typing of \railnonterm{vars} (due to
+  type-inference), and the naming of propositions (due to implicit
+  references of current facts).  In any case, Isar proof elements
+  usually admit to introduce multiple such items simultaneously.
+
+  \indexouternonterm{vars}\indexouternonterm{props}
+  \begin{rail}
+    vars: (name+) ('::' type)?
+    ;
+    props: thmdecl? (prop proppat? +)
+    ;
+  \end{rail}
+
+  The treatment of multiple declarations corresponds to the
+  complementary focus of \railnonterm{vars} versus
+  \railnonterm{props}.  In ``@{text "x\<^sub>1 \<dots> x\<^sub>n :: \<tau>"}''
+  the typing refers to all variables, while in @{text "a: \<phi>\<^sub>1 \<dots>
+  \<phi>\<^sub>n"} the naming refers to all propositions collectively.
+  Isar language elements that refer to \railnonterm{vars} or
+  \railnonterm{props} typically admit separate typings or namings via
+  another level of iteration, with explicit @{keyword_ref "and"}
+  separators; e.g.\ see @{command "fix"} and @{command "assume"} in
+  \secref{sec:proof-context}.
+*}
+
+
+subsection {* Antiquotations \label{sec:antiq} *}
+
+text {*
+  \begin{matharray}{rcl}
+    @{antiquotation_def "theory"} & : & \isarantiq \\
+    @{antiquotation_def "thm"} & : & \isarantiq \\
+    @{antiquotation_def "prop"} & : & \isarantiq \\
+    @{antiquotation_def "term"} & : & \isarantiq \\
+    @{antiquotation_def const} & : & \isarantiq \\
+    @{antiquotation_def abbrev} & : & \isarantiq \\
+    @{antiquotation_def typeof} & : & \isarantiq \\
+    @{antiquotation_def typ} & : & \isarantiq \\
+    @{antiquotation_def thm_style} & : & \isarantiq \\
+    @{antiquotation_def term_style} & : & \isarantiq \\
+    @{antiquotation_def "text"} & : & \isarantiq \\
+    @{antiquotation_def goals} & : & \isarantiq \\
+    @{antiquotation_def subgoals} & : & \isarantiq \\
+    @{antiquotation_def prf} & : & \isarantiq \\
+    @{antiquotation_def full_prf} & : & \isarantiq \\
+    @{antiquotation_def ML} & : & \isarantiq \\
+    @{antiquotation_def ML_type} & : & \isarantiq \\
+    @{antiquotation_def ML_struct} & : & \isarantiq \\
+  \end{matharray}
+
+  The text body of formal comments (see also \secref{sec:comments})
+  may contain antiquotations of logical entities, such as theorems,
+  terms and types, which are to be presented in the final output
+  produced by the Isabelle document preparation system (see also
+  \secref{sec:document-prep}).
+
+  Thus embedding of ``@{text "@{term [show_types] \"f x = a + x\"}"}''
+  within a text block would cause
+  \isa{{\isacharparenleft}f{\isasymColon}{\isacharprime}a\ {\isasymRightarrow}\ {\isacharprime}a{\isacharparenright}\ {\isacharparenleft}x{\isasymColon}{\isacharprime}a{\isacharparenright}\ {\isacharequal}\ {\isacharparenleft}a{\isasymColon}{\isacharprime}a{\isacharparenright}\ {\isacharplus}\ x} to appear in the final {\LaTeX} document.  Also note that theorem
+  antiquotations may involve attributes as well.  For example,
+  @{text "@{thm sym [no_vars]}"} would print the theorem's
+  statement where all schematic variables have been replaced by fixed
+  ones, which are easier to read.
+
+  \begin{rail}
+    atsign lbrace antiquotation rbrace
+    ;
+
+    antiquotation:
+      'theory' options name |
+      'thm' options thmrefs |
+      'prop' options prop |
+      'term' options term |
+      'const' options term |
+      'abbrev' options term |
+      'typeof' options term |
+      'typ' options type |
+      'thm\_style' options name thmref |
+      'term\_style' options name term |
+      'text' options name |
+      'goals' options |
+      'subgoals' options |
+      'prf' options thmrefs |
+      'full\_prf' options thmrefs |
+      'ML' options name |
+      'ML\_type' options name |
+      'ML\_struct' options name
+    ;
+    options: '[' (option * ',') ']'
+    ;
+    option: name | name '=' name
+    ;
+  \end{rail}
+
+  Note that the syntax of antiquotations may \emph{not} include source
+  comments @{verbatim "(*"}~@{text "\<dots>"}~@{verbatim "*)"} or verbatim
+  text @{verbatim "{"}@{verbatim "*"}~@{text "\<dots>"}~@{verbatim
+  "*"}@{verbatim "}"}.
+
+  \begin{descr}
+  
+  \item [@{text "@{theory A}"}] prints the name @{text "A"}, which is
+  guaranteed to refer to a valid ancestor theory in the current
+  context.
+
+  \item [@{text "@{thm a\<^sub>1 \<dots> a\<^sub>n}"}] prints theorems
+  @{text "a\<^sub>1 \<dots> a\<^sub>n"}.  Note that attribute specifications
+  may be included as well (see also \secref{sec:syn-att}); the
+  @{attribute_ref no_vars} rule (see \secref{sec:misc-meth-att}) would
+  be particularly useful to suppress printing of schematic variables.
+
+  \item [@{text "@{prop \<phi>}"}] prints a well-typed proposition @{text
+  "\<phi>"}.
+
+  \item [@{text "@{term t}"}] prints a well-typed term @{text "t"}.
+
+  \item [@{text "@{const c}"}] prints a logical or syntactic constant
+  @{text "c"}.
+  
+  \item [@{text "@{abbrev c x\<^sub>1 \<dots> x\<^sub>n}"}] prints a constant
+  abbreviation @{text "c x\<^sub>1 \<dots> x\<^sub>n \<equiv> rhs"} as defined in
+  the current context.
+
+  \item [@{text "@{typeof t}"}] prints the type of a well-typed term
+  @{text "t"}.
+
+  \item [@{text "@{typ \<tau>}"}] prints a well-formed type @{text "\<tau>"}.
+  
+  \item [@{text "@{thm_style s a}"}] prints theorem @{text a},
+  previously applying a style @{text s} to it (see below).
+  
+  \item [@{text "@{term_style s t}"}] prints a well-typed term @{text
+  t} after applying a style @{text s} to it (see below).
+
+  \item [@{text "@{text s}"}] prints uninterpreted source text @{text
+  s}.  This is particularly useful to print portions of text according
+  to the Isabelle {\LaTeX} output style, without demanding
+  well-formedness (e.g.\ small pieces of terms that should not be
+  parsed or type-checked yet).
+
+  \item [@{text "@{goals}"}] prints the current \emph{dynamic} goal
+  state.  This is mainly for support of tactic-emulation scripts
+  within Isar --- presentation of goal states does not conform to
+  actual human-readable proof documents.
+
+  Please do not include goal states into document output unless you
+  really know what you are doing!
+  
+  \item [@{text "@{subgoals}"}] is similar to @{text "@{goals}"}, but
+  does not print the main goal.
+  
+  \item [@{text "@{prf a\<^sub>1 \<dots> a\<^sub>n}"}] prints the (compact)
+  proof terms corresponding to the theorems @{text "a\<^sub>1 \<dots>
+  a\<^sub>n"}. Note that this requires proof terms to be switched on
+  for the current object logic (see the ``Proof terms'' section of the
+  Isabelle reference manual for information on how to do this).
+  
+  \item [@{text "@{full_prf a\<^sub>1 \<dots> a\<^sub>n}"}] is like @{text
+  "@{prf a\<^sub>1 \<dots> a\<^sub>n}"}, but displays the full proof terms,
+  i.e.\ also displays information omitted in the compact proof term,
+  which is denoted by ``@{text _}'' placeholders there.
+  
+  \item [@{text "@{ML s}"}, @{text "@{ML_type s}"}, and @{text
+  "@{ML_struct s}"}] check text @{text s} as ML value, type, and
+  structure, respectively.  The source is displayed verbatim.
+
+  \end{descr}
+
+  \medskip The following standard styles for use with @{text
+  thm_style} and @{text term_style} are available:
+
+  \begin{descr}
+  
+  \item [@{text lhs}] extracts the first argument of any application
+  form with at least two arguments -- typically meta-level or
+  object-level equality, or any other binary relation.
+  
+  \item [@{text rhs}] is like @{text lhs}, but extracts the second
+  argument.
+  
+  \item [@{text "concl"}] extracts the conclusion @{text C} from a rule
+  in Horn-clause normal form @{text "A\<^sub>1 \<Longrightarrow> \<dots> A\<^sub>n \<Longrightarrow> C"}.
+  
+  \item [@{text "prem1"}, \dots, @{text "prem9"}] extract premise
+  number @{text "1, \<dots>, 9"}, respectively, from from a rule in
+  Horn-clause normal form @{text "A\<^sub>1 \<Longrightarrow> \<dots> A\<^sub>n \<Longrightarrow> C"}
+
+  \end{descr}
+
+  \medskip
+  The following options are available to tune the output.  Note that most of
+  these coincide with ML flags of the same names (see also \cite{isabelle-ref}).
+
+  \begin{descr}
+
+  \item[@{text "show_types = bool"} and @{text "show_sorts = bool"}]
+  control printing of explicit type and sort constraints.
+
+  \item[@{text "show_structs = bool"}] controls printing of implicit
+  structures.
+
+  \item[@{text "long_names = bool"}] forces names of types and
+  constants etc.\ to be printed in their fully qualified internal
+  form.
+
+  \item[@{text "short_names = bool"}] forces names of types and
+  constants etc.\ to be printed unqualified.  Note that internalizing
+  the output again in the current context may well yield a different
+  result.
+
+  \item[@{text "unique_names = bool"}] determines whether the printed
+  version of qualified names should be made sufficiently long to avoid
+  overlap with names declared further back.  Set to @{text false} for
+  more concise output.
+
+  \item[@{text "eta_contract = bool"}] prints terms in @{text
+  \<eta>}-contracted form.
+
+  \item[@{text "display = bool"}] indicates if the text is to be
+  output as multi-line ``display material'', rather than a small piece
+  of text without line breaks (which is the default).
+
+  \item[@{text "break = bool"}] controls line breaks in non-display
+  material.
+
+  \item[@{text "quotes = bool"}] indicates if the output should be
+  enclosed in double quotes.
+
+  \item[@{text "mode = name"}] adds @{text name} to the print mode to
+  be used for presentation (see also \cite{isabelle-ref}).  Note that
+  the standard setup for {\LaTeX} output is already present by
+  default, including the modes @{text latex} and @{text xsymbols}.
+
+  \item[@{text "margin = nat"} and @{text "indent = nat"}] change the
+  margin or indentation for pretty printing of display material.
+
+  \item[@{text "source = bool"}] prints the source text of the
+  antiquotation arguments, rather than the actual value.  Note that
+  this does not affect well-formedness checks of @{antiquotation
+  "thm"}, @{antiquotation "term"}, etc. (only the @{antiquotation
+  "text"} antiquotation admits arbitrary output).
+
+  \item[@{text "goals_limit = nat"}] determines the maximum number of
+  goals to be printed.
+
+  \item[@{text "locale = name"}] specifies an alternative locale
+  context used for evaluating and printing the subsequent argument.
+
+  \end{descr}
+
+  For boolean flags, ``@{text "name = true"}'' may be abbreviated as
+  ``@{text name}''.  All of the above flags are disabled by default,
+  unless changed from ML.
+
+  \medskip Note that antiquotations do not only spare the author from
+  tedious typing of logical entities, but also achieve some degree of
+  consistency-checking of informal explanations with formal
+  developments: well-formedness of terms and types with respect to the
+  current theory or proof context is ensured here.
+*}
+
+
+subsection {* Tagged commands \label{sec:tags} *}
+
+text {*
+  Each Isabelle/Isar command may be decorated by presentation tags:
+
+  \indexouternonterm{tags}
+  \begin{rail}
+    tags: ( tag * )
+    ;
+    tag: '\%' (ident | string)
+  \end{rail}
+
+  The tags @{text "theory"}, @{text "proof"}, @{text "ML"} are already
+  pre-declared for certain classes of commands:
+
+ \medskip
+
+  \begin{tabular}{ll}
+    @{text "theory"} & theory begin/end \\
+    @{text "proof"} & all proof commands \\
+    @{text "ML"} & all commands involving ML code \\
+  \end{tabular}
+
+  \medskip The Isabelle document preparation system (see also
+  \cite{isabelle-sys}) allows tagged command regions to be presented
+  specifically, e.g.\ to fold proof texts, or drop parts of the text
+  completely.
+
+  For example ``@{command "by"}~@{text "%invisible auto"}'' would
+  cause that piece of proof to be treated as @{text invisible} instead
+  of @{text "proof"} (the default), which may be either show or hidden
+  depending on the document setup.  In contrast, ``@{command
+  "by"}~@{text "%visible auto"}'' would force this text to be shown
+  invariably.
+
+  Explicit tag specifications within a proof apply to all subsequent
+  commands of the same level of nesting.  For example, ``@{command
+  "proof"}~@{text "%visible \<dots>"}~@{command "qed"}'' would force the
+  whole sub-proof to be typeset as @{text visible} (unless some of its
+  parts are tagged differently).
+*}
+
+end




