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1

A digits_constraint
may be used to define a floating point subtype with a new value for its
requested decimal precision, as reflected by its Digits attribute. Similarly,
a delta_constraint may be used to
define an ordinary fixed point subtype with a new value for its *delta*,
as reflected by its Delta attribute.

1.a

2

3

{*expected type (delta_constraint
expression)* [partial]} The expression
of a delta_constraint is expected
to be of any real type.

4

The expression
of a delta_constraint shall be static.

5

For a subtype_indication
with a delta_constraint, the subtype_mark
shall denote an ordinary fixed point subtype.

6

{*notwithstanding*}
For a subtype_indication
with a digits_constraint, the subtype_mark
shall denote either a decimal fixed point subtype or a floating point
subtype (notwithstanding the rule given in 3.5.9
that only allows a decimal fixed point subtype).

6.a

7

A subtype_indication
with a subtype_mark that denotes
an ordinary fixed point subtype and a delta_constraint
defines an ordinary fixed point subtype with a *delta* given by
the value of the expression of the
delta_constraint. If the delta_constraint
includes a range_constraint, then
the ordinary fixed point subtype is constrained by the range_constraint.

8

A subtype_indication
with a subtype_mark that denotes
a floating point subtype and a digits_constraint
defines a floating point subtype with a requested decimal precision (as
reflected by its Digits attribute) given by the value of the expression
of the digits_constraint. If the
digits_constraint includes a range_constraint,
then the floating point subtype is constrained by the range_constraint.

9

{*compatibility (delta_constraint
with an ordinary fixed point subtype)* [partial]} A
delta_constraint is *compatible*
with an ordinary fixed point subtype if the value of the expression
is no less than the *delta* of the subtype, and the range_constraint,
if any, is compatible with the subtype.

10

{*compatibility (digits_constraint
with a floating point subtype)* [partial]} A
digits_constraint is *compatible*
with a floating point subtype if the value of the expression
is no greater than the requested decimal precision of the subtype, and
the range_constraint, if any, is
compatible with the subtype.

11

{*elaboration (delta_constraint)*
[partial]} The elaboration of a delta_constraint
consists of the elaboration of the range_constraint,
if any.

11.a

11.b

In Ada 83, a delta_constraint
is called a fixed_point_constraint, and a digits_constraint
is called a floating_point_constraint. We have adopted other terms because
digits_constraints apply primarily
to decimal fixed point types now (they apply to floating point types
only as an obsolescent feature).