Rendering the attached customer file with CVS HEAD gives many of the missing glyph boxes instead of spaces. Preview and Adobe Reader have no problems with this file. This is not a high priority for the customer, since this came out in internal testing.
Created attachment 1193 [details] Chroma-parameterchart.pdf
See also the bug 687510.
The file contains tab characters (\t) that apparently is not in the embedded font (Helvetica-Bold subset, Truetype format). The font has a .notdef character and this character is the rectangular box. We suspect that Adobe is using their own .notdef character that is a null character (a character that produces no space). It may be that Adobe is using Helvetica-Bold from their own font (on the system) rather than using the embedded font. We confirm that the embedded font contains the .notdef that is a box. Apparently Adobe Reader chooses to ignore the .notdef in the font and instead displays nothing.
Created attachment 1202 [details] file with munged fontname This file was prepared by (a) expanding compressed streams using pdfclean -x, and (b) doing a global search-and-replace of "Helvetica" to "Helvutica", so as to defeat any font substitution in the viewer. It renders in Acrobat 5 as a space, which seems to be inconsistent with section 5.5.5 of the PDF rendering, which specifies that .notdef is drawn.