Use A4 instead of US Letter paper size by default for PostScript output. This option has effect only if libpaper USE flag is disabled

Packages describing “metric” as local USE flag

Package “metric” Flag Description
app-text/xpdf Use A4 instead of US Letter paper size by default for PostScript output. This option has effect only if libpaper USE flag is disabled
media-gfx/potrace default to a4 paper size and metric measurement
sci-geosciences/gmt Use SI (cm) units instead of US (inches) ones

All packages providing a “metric” USE flag (2)