Chinese Plane
Small square wood with lightly chamfered edges all around. Chip hole: 3.1x2 cm. Conical slot for the iron behind it. Mouth: 0.6x2.4 cm. No wooden wedge.

Iron: 67 mm long, width: 27 mm at the top, 24 mm at the bottom.
Thickness: 6 mm at the top, 3 mm at the bottom. Blade: 20 mm, as the bevel is chamfered 2 mm on both sides at the bottom.

Cutting angle: 40°

Mark: Chinese characters engraved

The characters in the image are written in traditional Chinese. Here is the transcription and translation:

松: Pine
香: Fragrance
紫: Purple
檀: Sandalwood
(often associated with high quality)

The characters "松香紫檀" likely refer to "fragrant pine and purple sandalwood," which are valued types of wood known for their quality and scent. Purple sandalwood (紫檀) is a term commonly used to refer to a type of hardwood that is prized for its use in fine furniture and woodcraft, known for its deep purple hue after polishing.

Given that this is on a woodworking plane, it may indicate the type of wood the plane was intended to be used with, the type of wood from which the plane is made, or simply be a brand or maker's mark indicating a name or quality standard.