0.5
...bet it's the size of the point! (nib) A 7 would be a wider point than a 5...if it follows the standard. When you get down to a .001, for instance, you are looking at a fine pen for fine work. Some manufacturers go way down...I have some 005's.
07
Poison Pen - film - was created on 1939-07-04.
V-VII-MMV
17th
The date 05-24-07 is written as V-XXIV-VII or 05-24-2007 as V-XXIV-MMVII
Today - 1952 - 2002-05-07 was released on: USA: 7 May 2002
Today - 1952 - 2002-07-05 was released on: USA: 5 July 2002
Sexcetera - 1998 2005-05-07 was released on: USA: 7 May 2005
Hannity - 2009 2010-05-07 was released on: USA: 7 May 2010
Hannity - 2009 2009-05-07 was released on: USA: 7 May 2009
Today - 1952 2002-05-07 was released on: USA: 7 May 2002