In dotted decimal format, each syntax element is
written on a separate line. If two or more syntax elements are always present
together (or always absent together), they can appear on the same line, because
they can be considered as a single compound syntax element.
Each line
starts with a dotted decimal number, for example 3 or 3.1 or 3.1.1. To
hear these numbers correctly, make sure that your screen reader is set to
read out punctuation. All the syntax elements that have the same dotted decimal
number (for example, all the syntax elements that have the number 3.1)
are mutually exclusive alternatives. For example, if you hear the lines 3.1
USERID, 3.1 SYSTEMID, you know that your syntax
can include either USERID or SYSTEMID, but
not both.
The dotted decimal numbering level denotes the level of
nesting. For example, if a syntax element with the dotted decimal number 3 is
followed by a series of syntax elements with the dotted decimal number 3.1,
all the syntax elements numbered 3.1 are subordinate to the
syntax element numbered 3.
Characters such as commas
that are used to separate a string of syntax elements are shown in the syntax
just before the items that they separate. They can appear on the same line
as each item, or on a separate line with the same dotted decimal number as
the relevant items. The line might also show another symbol giving information
about the syntax elements; all these symbols are explained below. For example,
the lines 5.1* ,, 5.1 LASTRUN, 5.1
DELETE mean that if you use more than one of the syntax elements LASTRUN and DELETE,
they must be separated by a comma. If no separator is given, assume that you
use a blank to separate each syntax element.
If a syntax element is
preceded by the % symbol, this indicates a reference that
is defined elsewhere. The string following the % is the name
of a syntax fragment, rather than a literal. For example, the line 2.1
%OP1 means that, at this point, you must refer to the separate syntax
fragment OP1. OP1, in the syntax from which
this example was taken, gave a list of further options.
Certain words
and symbols are used next to the dotted decimal numbers to add information
about the syntax elements. Occasionally, these words and symbols might occur
at the beginning of the element itself. For ease of identification, if the
word or symbol is a part of the syntax element, it is preceded by the escape
character, which is a \ (backslash). For example, the * symbol
can be used next to a dotted decimal number to mean that this syntax element
can be repeated. If a syntax element actually starts with the * symbol,
for example a syntax element * FILE with the dotted decimal
number 3, it is given in the format 3 \* FILE. If the format
is 3* FILE, this means that there is a syntax element FILE,
which can be repeated. If the format is 3* \* FILE, this
means that there is a syntax element * FILE, which can be
repeated.
The words and symbols used next to the dotted decimal numbers
are as follows:
- ? means an optional syntax element. If a dotted
decimal number is followed by the ? symbol, this means that
all the syntax elements with that dotted decimal number, and any subordinate
syntax elements that they each have, are optional. If there is only one syntax
element with that dotted decimal number, the ? symbol appears
on the same line as the syntax element, for example 5? NOTIFY.
If there is more than one syntax element with that dotted decimal number,
the ? symbol appears on a line by itself, followed by the
syntax elements that are optional. For example, if you hear the lines 5
?, 5 NOTIFY, 5 UPDATE, you know
that the syntax elements NOTIFY and UPDATE are
optional; you can choose one or none of them. The ? symbol
is equivalent to a bypass line in a railroad diagram.
- ! means a default syntax element. If a dotted
decimal number is followed by the ! symbol, appended to the
last digit of the dotted decimal number, this means that this syntax element
is the default of all the elements with the same dotted decimal number. Only
one of the syntax elements that share the same dotted decimal number can specify
a !. For example, if you hear the lines 2? FILE, 2.1!
(KEEP), 2.1 (DELETE), you know that (KEEP) is
the default option for the FILE keyword. If you include the FILE keyword,
but do not state your choice of option, the default option KEEP is
applied. As well as the particular syntax element marked with the ! symbol,
the default also applies to the next higher dotted decimal number. In the
example above, the default applies to 2? FILE as well as
to 2.1! (KEEP), meaning that, if you omit the word FILE,
the default FILE(KEEP) is used. However, you might instead
hear the lines 2? FILE, 2.1, 2.1.1!
(KEEP), 2.1.1 (DELETE). As the default only applies
to the next higher dotted decimal number, which in this case is 2.1,
it does not apply to 2? FILE. In this case, if you omit the
word FILE, nothing is used.
- * means a syntax element that is optional and can
be repeated. If a dotted decimal number is followed by the * symbol,
this means that this syntax element is optional, and can be repeated. For
example, if you hear the line 5.1* data-area, you know that
you can include more than one data area, or you can include none. If you hear
the lines 3*, 3 HOST, 3 STATE,
you know that you can include HOST, STATE,
both, or nothing. If a dotted decimal number has an asterisk next to it, and
there is only one item with that dotted decimal number, you can repeat that
same item more than once. If a dotted decimal number has an asterisk next
to it, and several items have that dotted decimal number, you can use more
than one item from the list, but you cannot use the items more than once each.
In the example above, you could write HOST STATE, but you
could not write HOST HOST. The * symbol
is equivalent to a loopback line in a railroad syntax diagram.
- + means a syntax element that must be included at
least once, and can be repeated. If a dotted decimal number is followed
by the + symbol, this means that this syntax element must
be included at least once, and can be repeated. For example, if you hear the
line 6.1+ data-area, you know that you must include at least
one data area, and you can include more than one. If you hear the lines 2+, 2
HOST, 2 STATE, you know that you must include HOST, STATE,
or both. As for the + symbol, you can only repeat a particular
item if it is the only item with that dotted decimal number. The + symbol,
like the * symbol, is equivalent to a loopback line in a
railroad syntax diagram.