Parameters

symbol-name

   Specifies a string of 1 to 255 characters for the symbol name.
   The name can contain any alphanumeric characters from the DEC
   Multinational character set, the underscore (_),  and the dollar
   sign ($).  However, the name must begin only with an alphabetic
   character (uppercase and lowercase characters are equivalent),
   an underscore, or a dollar sign. Using one equal sign (=)  places
   the symbol name in the local symbol table for the current command
   level. Using two equal signs (==) places the symbol name in the
   global symbol table.


expression

   Names the value on the right-hand side of an assignment
   statement. This parameter can consist of a character string, an
   integer, a symbol name, a lexical function, or a combination of
   these entities. The components of the expression are evaluated,
   and the result is assigned to the symbol. All literal character
   strings must be enclosed in quotation marks (" ").  If the
   expression contains a symbol, the expression is evaluated using
   the symbol's value.

   The result of expression evaluation is either a character string
   or a signed integer value. If the expression is evaluated as a
   string, the symbol is assigned a string value. If the expression
   is evaluated as an integer, the symbol is assigned an integer
   value. If the integer value exceeds the capacity of the 4-byte
   buffer that holds it, no error message is issued.

   For a summary of operators used in expressions, details on
   how to specify expressions, and details on how expressions are
   evaluated, see the OpenVMS User's Manual.

   DCL uses a buffer that is 1024 bytes long to hold an assignment
   statement and to evaluate the expression. The length of the
   symbol name, the expression, and the expression's calculations
   cannot exceed 1024 bytes.


[bit-position,size]

   States that a binary overlay is to be inserted in the current
   32-bit value of a symbol name. The current value of the symbol
   name is evaluated. Then, the specified number of bits is replaced
   by the result of the replacement expression. The bit position is
   the location relative to bit 0 at which the overlay is to occur.
   If the symbol you are overlaying is an integer, then the bit
   position must be less than 32. The sum of the bit position and
   the size must be less than or equal to 32.

   If the symbol you are overlaying is a string, then the bit
   position must be less than 6152. Because each character is
   represented using 8 bits, you can begin an overlay at any
   character through the 768th character. (The 768th character
   starts in bit position 6144.) The sum of the bit position and
   the size must be less than or equal to 6152.

   The size is the number of bits to be overlaid. If you specify a
   size that is greater than 32, DCL reduces the size to 32.

   The brackets are required notation; no spaces are allowed between
   the symbol name and the left bracket. Specify values for the bit
   position and size as integers.


replacement-expression

   Specifies the value that is used to overlay the symbol you are
   modifying. Specify the replacement expression as an integer.

   If the symbol you are modifying is an integer, the replacement
   expression defines a bit pattern that is overlaid on the value
   assigned to the symbol. If the symbol you are modifying is
   a character string, the result of the replacement expression
   defines a bit pattern that is overlaid on the specified bits
   of the character string. If the symbol you are modifying is
   undefined, the result of the replacement expression is overlaid
   on a null string.