I know you remember the classic definition of microstrip as a function of surface traces referenced only to one internal plane - either exposed to air or buried by solder mask. Likewise, stripline is a function of traces between two reference planes either centered or offset. Don't know what difference continuous or split planes make to these definitions but for possible functionality and performance factors. MoonMan --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------