IEEE double extended format

[David C. Knaak]

The IEEE standard 754 does not specify an exact format for double extended
but only gives some minimum requirements.  It appears to me that a de facto
standard has emerged:

    1 bit for the sign
   15 bits for the exponent
  112 bits for the fraction
  ---
  128 bits total
    1 implicit bit, so 113 bits for the significand

      exponent bias of +16383

My questions are:

1)  Do you think that this is the appropriate format for double extended?

2)  Do you know of any manufacturer that is going a different direction, 
    and if so, why?

3)  Is "quad format" an appropriate term for this format?

Thanks for your thoughts.

David Knaak
knaakacray.com