ISO 31-1

'ISO 31-1' is the part of international standard ISO 31 that defines names and symbols for quantities and units related to ''space and time''.
Its definitions include:

Quantity		Unit			Remarks
Name	Symbol	Name	Symbol	Definition
angle, (plane angle)	''α'', ''β'', ''γ'', ''θ'', ''φ''	radian	rad	1 rad = 1 m/m = 1
		degree	°	1° = π/180 rad	There is no space between the number and these superscript-style unit symbols. Decimal subdivision of degrees is preferable (i.e., 12.5° instead of 12°30′)
		arcminute	′	1′ = (1/60)°
		arcsecond	″	1″ = (1/60)′
solid angle	''Ω''	steradian	sr	1 sr = 1 m²/m² = 1
length	''l'', ''L''	metre	m	The metre is the length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a second; see speed of light
breadth	''b''
height	''h''
thickness	''d'', ''δ''
radius	''r'', ''R''
diameter	''d'', ''D''
length of path	''s''
distance	''d'', ''r''
cartesian coordinates	''x'', ''y'', ''z''
radius of curvature	''ϱ''
curvature	''ϰ''	reciprocal metre	m−1		''ϰ''=1/''ϱ''
area	''A''	square metre	m²		The units are (1 a = 100 m²) and hectare (1 ha = 100 a) are used for agrarian areas.
volume	''V''	cubic metre	m³
		litre	l, L	1 l = 1 dm³
time, time interval, duration	''t''	second	s	The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom	Representations of time of day are defined in ISO 8601.
		minute	min	1 min = 60 s
		hour	h	1 h = 60 min = 3 600 s
		day	d	1 d = 24 h = 86 400 s
angular velocity	''ω''	radian per second	rad/s		''ω''=d''φ''/d''t''
angular acceleration	''α''	radian per second squared	rad/s²		''α''=d''ω''/d''t''
velocity	''v'' (general symbol), ''c'' (propagation speed of waves), ''u'', ''v'', ''w'' (vector components of a velocity ''c'')	metre per second	m/s
acceleration	''a''	metre per second squared	m/s²
acceleration of free fall, acceleration due to gravity	''g''

Annex A of ISO 31-1 lists units of space and time based on the foot, pound and second. Annex B lists some other non-SI units of space and time, namely the gon, light year, astronomical unit, parsec, tropical year, and gal.