Sectoral measures prohibit specific activities, most often new debt above a stated maturity, new equity, or the supply of particular goods and services, while leaving other business with the same entity lawful. They are used where a full block would cause disproportionate collateral damage.
The consequence for detection is that the question stops being “is this counterparty listed” and becomes “is this particular transaction, of this tenor, in this sector, prohibited”. That is a harder question to automate, and structuring around a maturity limit or a service definition is a recognised evasion pattern.