The ornamental design for a placardholder, as shown and described.
FIG. 1 is a perspective view of the placard holder of the present invention. The clip that is shown in broken lines includes a pivoting arm in its closed position against the window and/or the right edge of the frame around the viewing window of the placard holder, and is omitted from the remaining views for clarity.
FIG. 2 is a front view of the placard holder of FIG. 1.
FIG. 3 is a bottom elevation view of the placard holder of FIG. 2.
FIG. 4 is a top elevation view of the placard holder of FIG. 2.
FIG. 5 is an enlarged right side elevation view of the placard holder of FIG. 2.
FIG. 6 is an enlarged left side elevation view of the placard holder of FIG. 2.
FIG. 7 is a rear elevation view of the placard holder of FIG. 2; and,
FIG. 8 is an exploded perspective view of the placard holder of FIG. 1.
FIGS. 1-8 show portions of the placard holder in broken lines. The broken lines show boundaries of the design and elements of the placard holder that form no part of the claimed design.