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In all numeric constants, the most significant digit is specified first. Leading "0"
characters are ignored by the modem. No spaces, hyphens, periods, commas,
parentheses, or other generally-accepted numeric formatting characters are permitted in
numeric constants; note in particular that no "H" suffix is appended to the end of
hexadecimal constants.
2.4.2.2 String Constants
String constants consist of a sequence of displayable IA5 characters, each in the range
from 2/0 to 7/15, inclusive, except for the characters '"' (IA5 2/2) and "\" (IA5 5/12). String
constants are bounded at the beginning and end by the double-quote character ('"', IA5
2/2).
Any character value may be included in the string by representing it as a backslash ("\")
character followed by two hexadecimal digits. For example, "\0D" is a string consisting of
the single character <CR> (IA5 0/13). If the "\" character itself is to be represented in a
string, it is encoded as "\5C". The double-quote character, used as the beginning and
ending string delimiter, is represented within a string constant as "\22".
A "null" string constant, or a string constant of zero length, is represented by two
adjacent delimiters ("").
2.4.2.3 Compound Values
Actions may have more than one subparameter associated with them, and parameters
may have more than one value.
These are known as "compound values", and their treatment is the same in both actions
and parameters. A compound value consists of any combination of numeric and string
values (as defined in the description of the action or parameter). The comma character
must be included as a separator, before the second and all subsequent values in the
compound value. If a value is not specified (i.e., defaults assumed), the required comma
separator must be specified; however, trailing comma characters may be omitted if all
associated values are also omitted.
2.4.3 Action commands
2.4.3.1 Action execution command syntax
There are two general types of action commands: those that have associated
subparameter values that affect only that invocation of the command, and those that
have no subparameters. If subparameters are associated with a command, the definition
of the action command indicates, for each subparameter, whether the specification of a
value for that subparameter is mandatory or optional. For optional subparameters, the
definition indicates the assumed (default) value for the subparameter if no value is
specified for that subparameter; the assumed value may be either a previous value (i.e.,
the value of an omitted subparameter remains the same as the previous invocation of
the same command, or is determined by a separate parameter or other mechanism), or
a fixed value (e.g., the value of an omitted subparameter is assumed to be zero).
Generally, the default value for numeric subparameters is 0, and the default value for
string subparameters is "" (empty string).
The following syntax is used for actions that have no subparameters:
+<name>
The following syntax is used for actions that have one subparameter:
+<name>[=<value>]
The following syntax is used for actions that have two or more subparameters:
+<name>[=<compound_value>]
For actions that accept subparameters, if all subparameters are defined as being
optional, and the default values for all subparameters are satisfactory, the data terminal
equipment (DTE) may use the first syntax above (i.e., omit the "=" from the action