Some pdf files will allow me to to copy text to the clipboard and others will not. Is there a rule for which files will allow and which ones will not? If it is scanned in without using OCR am I correct to assume it won't work? Also, if it was originally a word doc or was created with writer then it will go to the clipboard. Please help me to clarify this. Also, if there are hard rules on what will and won't work that would be great. Thanks.