About PDF/X-1a

PDF / X is an abbreviation of Portable Document Format eXchange, is a standard PDF that is optimized for printing applications.
Was developed by (CGATS) Committee for Graphic Arts Technical Standards.
Has the contents were eliminated as much as possible uncertainties, such as color and font on the print becomes a problem in the standard PDF.
Also in the PDF / X, and those with special emphasis on traditional printing process is PDF/X-1a, by providing the following constraints like, garbled, missing fonts, etc. No trouble when printing image prevents.

Please refer to the PDF if you want to create a PDF/X-1a compliant file using Adobe Acrobat 6.0, it has been provided "Guide to Creating PDF for printing that conforms to the PDF/X" from adobe, for example.