In 1935, Märklin displayed OO gauge rail way(scale was 1/87)

https://en.wikipedia.org/wiki/HO_scale#History
1) 1/87, 16.5mm gauge
H0 was created to meet these aims. For this new scale, a track
width of 16.5 mm was designed to represent prototypical standard
gauge track, and a model scale of 1:87 was chosen.

2) described at that time either as 00 or H0.
By as early as 1922 the firm Bing in Nuremberg, Germany, had been
marketing a "tabletop railway" for several years.
This came on a raised, quasi-ballasted track with a gauge of 16.5
mm, which was described at that time either as 00 or H0.

3)Trix Express(table top model) was displayed which was
described as Half Nought Gauge.
At the 1935 Leipzig Spring Fair, an electric tabletop railway,
Trix Express, was displayed to a gauge described as Half Nought
Gauge, which was then abbreviated as Gauge 00 ("nought-nought")

4)In 1935, Märklin displayed OO gauge rail way(scale was 1/87)
Märklin, another German firm, followed suit with its 00 gauge
railway for the 1935 Leipzig Autumn Fair. 👀
Rock54: Caution(BBR-MD5:0be15ced7fbdb9fdb4d0ce1929c1b82f)