What is "space-and-a-half"?

Name: Makoto Ueki
Email: makoto.ueki@gmail.com
Affiliation: JIS Working Group
Document: W2
Item Number: (none selected)
Part of Item: 
Comment Type: editorial
Summary of Issue: What is "space-and-a-half"?
Comment (Including rationale for any proposed change):
We need more details on "space-and-a-half". It is one of the jargon. We couldn't find an appropriate word in Japanese.

Proposed Change:
Need explanation.