• one of a supplied list of acceptable values, with unambiguous abbreviations accepted; or
• a numeric character string equivalent to a number, and the number must lie within a supplied range of acceptable values.

PARAM = CHARACTER $\ast$ ( $\ast$ ) (Given)

MAXVAL = INTEGER (Given)

VMIN = ? (Given)

VMAX = ? (Given)

OPTS = CHARACTER $\ast$ ( $\ast$ ) (Given)

VALUES( MAXVAL ) = CHARACTER $\ast$ ( $\ast$ ) (Returned)

STATUS = INTEGER (Given and Returned)

• There is a routine for each of the data types double precision, integer, and real: replace "x" in the routine name by D, I, or R respectively as appropriate. The VMIN and VMAX arguments must have the corresponding data type.

• There are two stages to identify or validate each character value obtained from the parameter.

  In the first the value is converted to the data type specified by the "x" in the routine name. If this is successful, the derived numeric value is compared with the range of acceptable values defined by VMIN and VMAX. A value satisfying these constraints is returned in the VALUES.

  The second stage searches for a match of the character value with an item in the menu. This step adheres to the following rules.

  • The value is converted to the data type specified by the "x" in the routine name. If this is successful, the numeric value is compared with the range of acceptable values defined by VMIN and VMAX. A value satisfying these constraints is returned and the matching process terminates.
  • All comparisons are performed in uppercase. Leading blanks are ignored.
  • A match is found when the value equals the full name of an option. This enables an option to be the prefix of another item without it being regarded as ambiguous. For example, "10,100,200" would be an acceptable list of options.
  • If there is no exact match, an abbreviation is acceptable. A comparison is made of the value with each option for the number of characters in the value. The option that best fits the value is declared a match, subject to two provisos. Firstly, there must be no more than one character different between the value and the start of the option. (This allows for a mistyped character.) Secondly, there must be only one best-fitting option. Whenever these criteria are not satisfied, the user is told of the error, and is presented with the list of options, before being prompted for a new value If a nearest match is selected, the user is informed unless the MSG filtering level (see SUN/104) is ‘quiet’.

  This routine exits when all the values satisfy the criteria.