Re Mil-P-13949.  The document is titled "Plastic Sheet, Laminated, Metal 
Clad (For Printed Wiring Boards), General Specification for." and as may be 
assumed by the title provides a technical description of several types of 
pwb laminate material.   I believe the document is available (cost free) 
from the "Naval Publications and Forms Center (Attn: NPODS), 5801 Tabor 
Ave., Philadelphia, PA 1920-5099".   I also thinke that for small orders (1 
or 2 documents) the folks will accept orders via phone or Fax. Phone No. 
(voice line) = 215/697-2667 or 2179 and Fax No. = 215/697-2978.  Hope  this 
helps.  JHM