Learn English – Should there be a space in e.g./i.e. between a dot

As I understand the official SI manual (which siunitix is supposed to follow), there should be a space, not a thin space, between the number and the unit:

The numerical value always precedes the unit, and a space is always used to separate the unit from the number. (section 5.3.3)

I also find that this seems to be the more common procedure in typed texts (but that might again be because most people don't know abut the thin space).

Just to be clear, the SI manual is aware of the thin space, cf. the following section 5.3.4:

Following the 9th CGPM (1948, Resolution 7) and the 22nd CGPM (2003, Resolution 10), for numbers with many digits the digits may be divided into groups of three by a thin space, in order to facilitate reading.

And precisely for this reason, the siunitix package has since this question was asked changed its setting from using a thin space to using a normal space, see this update.

In the US, it is common on business cards, letterheads and email signature blocks to list phone numbers as

(212) 321-7654 (tel)

(917) 654-3210 (cell)

(323) 999-8888 (fax)

Sometimes a period is added after tel, but rarely after fax and never after cell. Sometimes the first letter of the modifier is capitalized, but often not.

I have never seen mob in the US to define a cell phone and rarely see mobile in printed materials (although it is used often in speech).

In resumes (and other documents with headings) the number is sometimes preceded by the phone type, as in

Tel: (212) 987-6543

While there are some area codes (the first three numbers) that are reserved to cell phones, many area codes are used for land, cell, and fax, and people do not necessarily know which numbers are which, so marking is common.

If someone only uses a single line, land or mobile, the parenthetical is usually left off. There is a growing pattern in the US of giving up land lines and only using cells (especially among younger people). Such folks often simply list their number without referring to its type.