media box

Defines the location and size of the physical medium on which the page is intended to be displayed or printed.

bleed box

Defines the bounds to which the contents of the page should be clipped when output in a production environment. Default value is the page's crop box.

trim box

Defines the intended dimensions of the finished page after trimming. This may be smaller than the media box to allow for production-related content such as printing instructions, cut marks, or color bars. The default value is the page's crop box.

art box

Defines the extent of the page's meaningful content, including potential white space. Default value is the page's crop box.

crop box

Defines the region to which the contents of the page are to be clipped (or cropped) when displayed or printed. Unlike the other boxes, the crop box has no defined meaning in terms of physical page geometry or intended use, it merely suggests where the page should be clipped.

PDF/X-1a restrictions

PDF Preflight checks that files comply with PDF/X-1a:2001 standard.
In either of the following situations, you must specify either the art box or trim box.

The art box defines the extent of a page's meaningful content. If you are using only part of a page, the art box is the area of text, pictures, and needed white space. The rest of the page, which is blank, isn't considered.
If you are using the whole page, then you must specify the trim box, media box, and the bleed box. If the bleed box is not already defined, you can specify that the normalizer function set the bleed box to be equal to the media box.
Press layout specifications:

Minimum Trim to Bleed Margin: PDF Preflight checks whether the document contains predetermined or sufficient bleed.
Minimum Bleed to Media Margin: Refer to the preceding diagram to see how media margin is defined. PDF Preflight checks whether the document contains predetermined bleed.

Advanced Preflight Example

To set Prinergy to check the size of the trim box and check whether a bleed box is defined, perform the following steps.
In Preflight Profile Editor > Page > Layout:

With these settings, Prinergy checks whether a bleed box is defined. If it is not, Prinergy defines it during the refine process.