A nine inch Gunter

Data:

• probably made of boxwood
• 228mm (9 inches or ¾ feet) x 45mm.
• Front scales:
  • (left) (line 1) CHO 0-90, (2) LAT 0-90, (3) SIN 0-90, (4) I*M 0-90 and beyond, (5) TAN 0-70.5, (6) HOU 0-VI
  • (middle) (1) ? 0-5, (2) ? 0-9, (3) ? 0-6
  • (right) (1) RUM 0-8, (2) LON 60-0, (3) SEC 10-70, (6) ? 0-33
• Back scales:
  • English inch with decimal divisions
  • English foot with decimal divisions
  • Meridian scale (I think) with divisions in inches

Questions:

1. Only 9 inches long (and not 12 inches or 1 foot, or the standard 2 feet). Are other small Gunter rules known?
2. No (single or double) “Line of Numbers” or NUM scale. Why is this scale, Gunter's revolutionary invention, omitted?
3. What is the I*M scale ?
4. What is the HOU scale (Roman numeration)? The first letter “H” can also be a different letter.
   Scales for making sundials were the most distinctive feature of sectors made in England. These included scales for hours(HOU), chords (CHO), latitude(ALT), and the inclined meridian (I*M) Smithsonian NMAH
   “I*M” means “Inclination of Meridians” and “Hou” means “Hours” (but why only 0-VI ?)
   See William Mountaine, “A description of the lines drawn on Gunter's scale, as improved by Mr. John Robertson”, London, 1779, page 5, 84 Andries de Man
   William Mountaine points to a more extensive Gunter rule described by John Collins in “The sector on a quadrant, …”, London, 1659, plate after page 284 Andries de Man
   see also Michael Lowne, John Davis, “A horizontal quadrant of 1658 by Henry Sutton, Part 2”, BSS Bulletin Volume 23(iii) September 2011 page 45-48