Taken from PCGS' website:
Notes that have major faults such as tears, splits, holes, missing pieces or have been subject to major restoration, such as repaired tears or splits, redrawing of the design, bleaching of the paper, or even reconstruction of missing pieces, will be assigned a “problem note” designation. Such problems will be noted on the grading label. In these cases we will assign an “Apparent” grade followed by a brief and concise description of the problems or repairs. The “Apparent” grade will equate to what the note would have graded without the mentioned problems. For example, “Apparent VF30, bleached and starched” might be a description of a problem note, as might “Apparent XF45, upper-right corner restored”.