Nicholas, If the clearances were not there, you would have every layer shorted to each other.. Clearances are used to insure that any specific power or ground plane will not short to any other layer. The only time a clearance will not be there is when it is desired for that hole (net) to make a connection to that plane. Ron ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or 847-509-9700 ext.5365 ##############################################################