Units of NTv2 accuracy samples ?

NTv2 filename	Producer	Min/Mean/Max lat accuracy	Unit	Confirmed by producer
rdtrans2008/rdtrans2018.gsb	Kadaster Netherlands	1e-3 / 1e-3 / 1e-3	Metre	Yes
ntv2_0.gsb	NRCan Canada	0 / 0.27 / 13 (1st subgrid)	Metre	Yes
ntf_r93.gsb	IGN France	1.6e-4 / 0.035 / 0.065	Second	Yes
BWTA2017.gsb	LGL Germany	1.6e-5 / 6.3e-5 / 1.4e-4	Second	Yes
nzgd2kgrid0005.gsb	LINZ New Zealand	5.9e-4 / 0.03 / 0.1	Second	Yes
OSTN15_NTv2_OSGBtoETRS.gsb	Ordnance Survey Great Britain	1e-6 / 5e-6 / 3e-5	Second	Yes
bd72lb72_etrs89lb08.gsb	IGN Belgium	0.01 / 0.01 / 0.01	Metre	Yes
CHENyx06a.gsb	Swisstopo Switzerland	1e-3 / 1e-3 / 1e-3	Second	Yes
D73_ETRS89_geo.gsb	DGTerritorio Portugal	1.5e-3 / 1.5e-3 / 1.5e-3	Second	Yes
GDA94_GDA2020_conformal_and	ICSM Australia	1e-7 / 7e-4 / 3e-2 (1st subgrid)	Second	Yes
_distortion.gsb		Use nodata = -1
A66_National_13_09_01.gsb	ICSM Australia	1e-3 / 8e-3 / 1e-2 (1st subgrid)	Second	Yes
CA61_003.GSB	IBGE Brazil		Metre	Yes
CA7072_003.GSB	IBGE Brazil		Metre	Yes
SAD69_003.GSB	IBGE Brazil		Metre	Yes
SAD96_003.GSB	IBGE Brazil		Metre	Yes

Remarks:

• bd72lb72_etrs89lb08.gsb : documented by EPSG to have a 0.01 m accuracy
• D73_ETRS89_geo.gsb: the lat accuracy is 1.5e-3 and the lon accuracy is 1.9e-3. If using a latitude = 36 degree, 1.9e-3 * cos(36 degree) ~= 1.5 e-3. Hence a hint the unit might be seconds