A mid-rad interchange motion...

[Dan Zuras Intervals <intervals08@xxxxxxxxxxxxxx>]

	Folks,


	Arnold & I have been working offline on the text of a mid-rad
	interchange motion.  I think it is much improved.  And the credit
	for that goes much to Arnold.  Thank you Arnold.

	As it is now, we define two new terms: 'supported', meaning fully
	supported for all required operations (our intention for inf-sup)
	& 'available', meaning merely supported for conversion to & from
	(our intention for mid-rad & mid-rad1-rad2).

	The motion is pared down to just 3 shalls: (1) saying that one
	shall have at least one of each type, (2) saying that conversions
	shall tightly preserve containment, & (3) saying that importing
	from & exporting to text shall be tightly contained as well.

	There is also an informative note stating explicitly that the
	standard is silent on the issue of further support for available
	but not supported types.

	(I know: an explicit statement about being silent.  As Arnold
	puts it, it is the MOTION that is being explicit on what the
	STANDARD should be silent about.  He is right, of course.
	So gimme a break.  :-)

	So, I submit for your approval, from both of us, this motion
	for mid-rad as an interchange only type:

	---------------------------------------------------------------

	An interval type is said to be <b> supported </b> if all
	required operations are implemented as well as conversions to
	and from that type and any other type and import from and export
	to text strings.

	An interval type is said to be <b> available </b> if conversions
	to and from that type and any other type are implemented as well
	as import from and export to text strings.

	A conforming implementation shall support at least one inf-sup
	type and make available at least one mid-rad and one mid-rad1-rad2
	type.

	All conversions shall preserve containment and return the tightest
	representable interval in the target type.

	All imports shall preserve containment and return the tightest
	representable interval in the target type.  All exports shall
	preserve containment and return the tightest representable text
	string in the specified format.

	NOTE --- This standard is silent on the matter of other
	operations implemented for types that are available but not
	supported.

	---------------------------------------------------------------

	I have a special on friendly amendments at this time.
	This week only, two for the price of one.

	Enjoy,

				   Dan