You can use a floating-point number in the .DOUBLE, .FLOAT,
    .F_FLOATING, .D_FLOATING, .G_FLOATING, .S_FLOATING, and
    .T_FLOATING directives. You cannot use a floating-point number
    in an expression or with a unary or binary operator except the
    unary plus and unary minus.

    You can specify a floating-point number with or without an
    exponent.
    FORMAT
    Floating-point number without exponent:

    snn
    snn.nn
    snn.

    Floating-point number with exponent (E):

    snnEsnn
    snn.nnEsnn
    snn.Esnn

 s

    An optional sign.

 nn

    A string of decimal digits in the range of 0 to 9.

    The decimal point can appear anywhere to the right of the first
    digit. A floating-point number cannot start with a decimal point
    because MACRO-64 treats the number as a user-defined symbol.