[cairo] Cairo PDFs - vector or raster?

[C. Thomas Stover]

While looking deeper into the disconcerting world of printing and PDF 
files, I realized the model is a great deal more complex than I first 
imagined. Text in particular can be realized as either A) postscript that 
drives the PDF renderer's or printer rasterizer's font engine B) 
postscript defining vector graphics that form the shapes of glyphs 
(perhaps translated from scalable font formats) C) raster image / 
bitmaps. The problem with A is the lack of anything resembling Unicode 
support. 

Seeing as how pango + cairo can produce PDF and PS files with Unicode 
text, how is the text in those files encoded? As pixels, paths, or 
characters + font controls?

(yes I know I could look, but I'm hoping to learn something I haven't 
figured out yet by the responses)