1 Constants
 A constant is a numeric or character value that  does  not  change  during
 program execution.  BASIC accepts floating-point, integer, packed decimal,
 and character string constants.  You can create a named  constant  of  any
 data  type  with the DECLARE statement.  You can also use explicit literal
 notation to specify the value and data type of a numeric literal.

2 Literal_notation
 The format for explicit literal notation is:

     [radix] num-str-lit [data-type]

 Radix specifies an optional base and can be:

  o  D Decimal (base 10) - the default
  o  B Binary (base 2)
  o  O Octal (base 8)
  o  X Hexadecimal (base 16)
  o  A ASCII

 The numeric string can consist of digits and an optional decimal  point.
 You  can  also  use  E notation for floating-point constants.  A leading
 minus sign cannot appear inside the quotation marks.   Data  type  is  a
 single letter abbreviation a data type keyword:

  o  B BYTE
  o  W WORD
  o  L LONG
  o  Q QUAD
  o  F SINGLE
  o  D DOUBLE
  o  G GFLOAT
  o  S SFLOAT
  o  T TFLOAT
  o  X XFLOAT
  o  P DECIMAL

 Data type can also be C, which specifies a  single-character  string  in
 terms  of  its 8-bit ASCII value.  For the C data type, the value of the
 numeric string must be between 0 and 255, inclusive.  For example:

 B"11111111"B = BYTE binary constant (-1)
 X"FF"B       = BYTE hexadecimal constant (-1)
 O"377"B      = BYTE octal constant (-1)
 "7"C         = CHARACTER constant (ASCII decimal value 7)

2 Floating-point
 A floating-point constant is a literal or named  constant  with  one  or
 more  decimal  digits,  either positive or negative, an optional decimal
 point, and an exponent of 10 (E notation).  If the default data type  is
 INTEGER, a decimal point or an E is required or BASIC treats the literal
 as an integer.  If the default data type is DECIMAL, an E is required or
 BASIC treats the literal as a DECIMAL.

2 Integer
 An integer constant is a literal or named  constant  with  one  or  more
 digits,  either  positive  or negative, with no fractional digits and an
 optional trailing percent sign (%).  The percent sign  is  required  for
 integer literals if the default data type is not INTEGER.

2 Packed_Decimal
 A packed decimal constant is a number, either positive or negative, that
 has  a  specified  number  of  digits  (d) and a specified decimal point
 position (s).  You can specify the d and s values when you  declare  the
 constant  or use explicit literal notation.  If you do not specify d and
 s values, BASIC uses the current defaults for DECIMAL.

2 String
 String constants are either  string  literals  or  named  constants.   A
 string  literal  is  a series of characters enclosed in double quotation
 marks ("text") or single quotation marks ('text').  You can embed double
 quotation  marks within single quotation marks ('"text"') and vice versa
 ("'text'").  Note, however, that  the  outer  quotation  marks  must  be
 paired.

2 Named
 To name a constant within a program, use the DECLARE CONSTANT statement.
 To  name  a  constant  external  to a program, use the EXTERNAL CONSTANT
 statement.