If you look at an SFM Series Connector from Samtec, you may see that there is a notch at one end of the connector, such as SFM-115-02-L-D-A. This notch is designated to avoid incorrect mating orientations.
Some customers have unfortunately misidentified this shape as being for Pin 1 identification. According to the datasheet, Pin 1 is the opposite diagonal corner of this polarizing notch.
