    # KEHOME/doc/MKRtoken.html
    # Aug/12/2003

# MKR tokens
version 6.1

    # The MKR parser has three phases
    #
    # 1. token.icn: get_word(): identify low-level word classes, e.g.
    #	b	white space
    #	s	separator
    #	w	word
    # 2. token.icn: get_token(): identify special words and operators, e.g.
    #	A	at
    #	H	has isin
    #	D	do
    #	o	od
    #	d	done
    #	R	relation: isa isa* isa**n ...
    #	P	preposition: of with from to out
    #	=	assignment operator: =,+=,-=,*=
    # 3. symbol.icn: get_symbol(): identify phrases, sentences, ..., e.g.
    #	www;	word phrase
    #	wHw=w;	subject has attribute=value
    #	wRw;	subject rel object
    #	wiwPw=w;subject is  object with attribute=value

    #------------------------------------#
    # Here's the complete list of tokens #
    #------------------------------------#

    B	white space: blank tab return newline newpage
    N	non separator: ~ / \ ? . $  (included in w)
    W	weak separator: + - * :     (included in x)
    S	strong separator: , ; = ! & | [ ] { } ( ) < > " ' #
    w	word: consecutive bytes not B nor S nor W
    x	extended word: consecutive w or W

    "	quote mark: " or '
    q	quote
    #	comment mark: #
    c	comment

    # NOTE:
    # For high level parsing (phase 3 in symbol.icn),
    # the types above are remapped to
    #	B	=> deleted
    #	W	=> individual characters
    #	S	=> individual characters
    #	w	=> w
    #	x	=> w
    #	"	=> not used
    #	q	=> w
    #	#	=> not used
    #	c	=> deleted

    ,	list separator: phrase
    ;	list separator: sentence, proposition

    ~	OK in word: not
    :	OK in word: view-concept, class-number, unit
    +	OK in word
    -	OK in word
    *	OK in word: wildcard

    A	at: context -- space,time,view
    B	user-defined binary relation
    C	rdfs:Class
    D	do do* vdo
    d	done
    E	else
    F	fi
    G	generator: every,when,while
    g	group: ntriple,mcf,rdf,... (use begin/end)
    H	has isin haspart isapart
    h	hierarchy (use begin/end)
    I	if
    i	is isa iss isu isd isi
    J	conjunction: ";" iff implies causes means
    j	conjunction: and or
    N	complement: not non
    P	preposition: out of with from to od at
    p	rdf:Property
    Q	quantifier: a some the no all any either
    R	relation verb: isa* isa** ... isc isc* isc** ... in ...
    r	relation (use begin/end)
    S	assignment: set vset unset
    s	space
    T	then
    t	time
    U	unknown
    v	view
    w	word not predefined by MKR
    x	xml,rdf
    Y	group definition: begin
    Z	group definition: end
    z	exit

    ()	grouping: not currently used
    []	begin/end of comma list: phrase
    {}	begin/end of semicolon list: proposition
    <>	embedded HTML

    /	down one level in hierarchy
    \	up one level in hierarchy
    ?	question
    !	sh command
    $	value of variable
    $()	product (a la KornShell) -- not currently used
    ..	dot variable: current genus
    .	dot variable: current concept
    ...	dot variable: current species

    =	assignment operator =
    =	Set add operator +=
    =	Set delete operator -=
    =	Set intersection operator *=
    =	production operator :=
    =	Backus-Naur Form grammar operator ::=

    &	and, asynchronous execution (not implemented)
    |	or,  pipe (not implemented)
    ~	not, login directory

    ##### possible additions #####
    m	method
    o	od: direct object
    u	unit

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