| 摘要 |
PROBLEM TO BE SOLVED: To provide a bottom board in which one substrate conforms to both a jack base and a fixation base that can be selectively used.SOLUTION: One substrate is provided with: a jack base recess allowing arrangement of a square jack base; and a fixation base recess allowing installation of a square fixation base. The jack base recess and the fixation base recess are angularly shifted in the horizontal rotation direction. Each recess is depressed by one step from the top face of the substrate, is open toward the top face to allow the corresponding base to be placed from above the substrate, and comprises: a setting part allowing corner parts of the corresponding base to be set at the periphery of the recess; an entry-exit opening allowing the set base to be horizontally rotated for entry or exit; a rotation space allowing the horizontal rotation of the jack base or fixation base brought from the corresponding entry-exit opening; a rotation stopper that stops rotation of and positions the jack base or fixation base rotated in the rotation space; and an escape stopper that inhibits the positioned jack base or fixation base from escaping in the vertical direction.SELECTED DRAWING: Figure 1 |
