What does it mean to draw a blueprint with a moustache mark?

Cultural activities. The blueprint drawn with moustache markers was jointly organized by Jiangpu community. Giving full play to students' artistic expertise is a cultural activity. The activity invited young calligraphers from Anshan Junior High School and painters from Jiangpu Haiyi Painting and Calligraphy Institute to write Spring Festival couplets on the spot, and sent blessings to the community citizens who contributed to the creation of a national civilized city.