The part's number (must be URL encoded)

The storage asset's number (must be URL encoded)

The site the request acts on, e.g. s2. You find it in the remberg web app URL (e.g. /s2/) or next to the site name under Settings → Sites. If your account has access to more than one site, send this header on every request; site-specific requests without it fail with 403 ACTIVE_SITE_UNAVAILABLE. With access to a single site, that site is used when the header is omitted. A site your account cannot access fails with 403 ACTIVE_SITE_UNAVAILABLE; a record that belongs to another site returns 404.