+.Ar string2
+or both to specify characters, character ranges, character
+classes, or collating elements:
+.Bl -tag -width [[:equiv:]]
+.It character
+Represents that character.
+.It \eoctal
+A backslash followed by 1, 2, or 3 octal
+digits represents a character with that
+encoded value.
+If a \eoctal sequence is
+followed by digits, the backslash and up to
+three digits are interpreted to prepare a
+character; subsequent digits are interpreted
+as individual characters.
+.It \echaracter
+A backslash followed by any character except
+an octal digit represents that character.
+.It [c-c]
+Represents the range of ordered elements
+between the range endpoints, inclusive.
+.\" ; as
+.\" defined by the current setting of the
+.\" setlocale() category
+.\" .Em LC_COLLATE .
+.\" The collating
+.\" elements are ordered in ascending collating
+.\" sequence, and the first endpoint shall precede
+.\" the second in the collating sequence.
+.It [[:class:]]
+Represents all characters belonging to the
+defined character class.
+.\" as defined by the
+.\" current setting of the setlocale() category
+.\" .Ev LC_CTYPE .
+Allowable names for class are:
+.Bl -column alpha upper lower digit xdigit -offset indent
+alpha upper lower digit xdigit alnum
+space punct print graph cntrl
+.El
+.Pp
+The characters placed in ascending order.
+.\" .Em LC_COLLATE .
+.\" (Characters not defined in the
+.\" current collating sequence are ordered
+.\" according to the collation sequence's rules
+.\" for ordering of undefined characters.)
+.It [[=equiv=]]
+Represents all characters or collating (sorting)
+elements belonging to the same equivalence class
+as equiv.
+.\"
+.\"
+.\" .Em LC_COLLATE .
+If
+there is a secondary ordering within the
+equivalence class, the characters are ordered
+in ascending sequence.
+Otherwise, they are
+ordered after their encoded values.
+.It [[.cs.]]
+Represents a collating symbol.
+Multicharacter
+collating symbols shall be represented as
+collating symbols to distinguish them from a
+string of the same characters.
+.It [x*n]
+Represents n repeated occurrences of the
+character or collating symbol x.
+This
+expression is only valid when it occurs in
+.Ar string2 .
+If n is omitted or is zero, it is
+be interpreted as large enough to extend the
+.Ar string2 Ns -based
+sequence to the length of the
+.Ar string1 Ns -based
+sequence.
+If n has a leading
+zero, it shall be interpreted as an octal
+value.
+Otherwise, it shall be interpreted as
+a decimal value.
+.El
+.Pp
+Characters belonging to an equivalence class occupy the same
+position in the sequence, ordered after secondary ordering.
+.Pp
+The
+.Nm tr
+utility exits with one of the following values:
+.Bl -tag -width Ds
+.It 0
+All input was processed successfully.
+.It 1
+An error occurred.
+.El
+.Sh STANDARDS
+The
+.Nm tr
+utility is expected to be
+.Tn POSIX
+1003.2 compatible.