Multi-function instruments are generally classified according to their principal function. A pen that also incorporates a touchscreen stylus tip would typically be classified as a pen if writing is the primary marketed function. When functions are genuinely equal, classification follows the heading that appears last in numerical order among those applicable. Detailed product specifications and marketing materials help support the classification position.

Customs value must reflect the transaction value of the complete pen as imported, including any precious-metal nib, cap, or barrel. If the pen is sold as part of a gift set with a case or accessories, the value of the entire set must be declared unless the components are separately classified and invoiced. Importers of high-value writing instruments should ensure commercial invoices itemize unit values accurately to avoid undervaluation findings.