It is not legal to simply state that a component is a trade secret. An alternative name must be requested from ECHA under Article 24 of CLP Regulation and that name used.
Annex I of CLP Regulation defines in Section 1.4 when requests for use of an alternative chemical name under Article 24 may be granted.
For instance, a substance classified as a skin sensitiser, as well as Aq acute 1/Aq chronic 1, is disqualified it from the Article 24 process.
Relationship between GHS and CLP: GHS specifies that rules of the importing country apply with respect to CBI claims. This means that CLP applies, and hence Article 24 provisions apply.
Substances classified as skin sensitisers (H317) are most often problematic in SDSs prepared in non-EU countries. Thus, in the case where a substance is classified as a skin sensitiser, the identity of the substance cannot be held secret and the supplier of that substance in a mixture must use the exact chemical name for the substance on the label and in the safety data sheet, and not the alternative chemical name.