<matrix> :==
<vector> :==
<symbol> :== ${<alphanumeric>|.|_}
<parameter> :== &{<alphanumeric>|.|_}
<literal-constant> :== <complex> | <real> | <integer> | <logical> | <word>
<format> :== {<alphanumeric>|.}
<filename> :== <word>
<buffername> :== <word>
<procedurename> :== <word>
<classname> :== <word>
<groupname> :== <word>
<segid> :== [<alphanumeric>][<alphanumeric>][<alphanumeric>][<alphanumeric>]
<resname> :== <alphanumeric>[<alphanumeric>][<alphanumeric>][<alphanumeric>]
<resid> :== <alphanumeric>[<alphanumeric>][<alphanumeric>][<alphanumeric>]
<type> :== <alphanumeric>[<alphanumeric>][<alphanumeric>][<alphanumeric>]
<atom> :== <alphanumeric>[<alphanumeric>][<alphanumeric>][<alphanumeric>]
<reference> :== <number>|+|-
<wildcard> :== {<alphanumeric>|*|%|#|+}
<complex> :== ( <real> [,] <real> )
<real> :==
<integer> :== [+|-]{<number>}
<logical> :== true | false
<string> :==
<word> :==
<alphanumeric> :== <letter>|<number>
<number> :== 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9
<letter> :== A - Z | a - z
<character> :== _ | # | % | : | ; | ` | ? | .
<quotable> :==
<whitespace> :== space | tab