Eric is right. The profile should maximize tonal separation at the ends of the scale. In practice this requires multiple readings of shadow patches in particular before building the profile. This precaution often separates excellent custom profiles from poor ones. Perhaps due to time expediency , the latter , unfortunately abound.
Production of a clipping curve negates the effectiveness of the profile and prevents the attainment of max. black.
In practice sometimes a small reduction of white is useful to prevent blank highlights, which show as surface effects on some papers in files that are themselves a little clipped. The eye/mind resets it's own white point.
In cases where shadows are clipped on the file I find it preferable to lower Color Density 10-20% in
Paper Configuration (Ep 9800, PS/Print) rather than adjust curves which lowers global contrast.
Cheers,
Brian,
www.pharoseditions.com.au