Scientific Number Format

It is well known that locales vary in how numbers are formatted.
   en_US   123.45
   fr_FR   123,45

Does this extend to the technical and scientific community? Would
the French user of a device prefer to see 5,5 or 5.5 when representing
volts or degrees centigrade?

A quick survey of web sites in the .fr domain shows both
representations are used. What is the best use for the French
customer.

Also, do technical and scientific users want to see thousand
separators?

-paul