PANTONE Item grayed out under File/Export function

In PANTONE Color Manager, under File/Export, PANTONE is grayed out and I can only choose L*a*b* or sRGB. Why?

The PANTONE item is grayed out because it is not a choice;. Both L*a*b* and sRGB are PANTONE spot color options.

L*a*b* is the basic color space for color-managed print workflow and is the recommended choice for most users.

sRGB is the default space for the Web.