圖釘

thumbtack

diagram / picture / drawing / chart / map / CL:張|张[zhang1] / to plan / to scheme / to attempt / to pursue / to seek

nail / to follow closely / to keep at sb (to do sth) / variant of 盯[ding1]

to join things together by fixing them in place at one or more points / to nail / to pin / to staple / to sew on