Citroen C3 - How to Read The Solenoid Screw Size?

Hi All,

I am a newbie car DIY enthusiastic.

I just need some guidance in how to read the "Self Tap screw" size used to tighten the Exhaust solenoid on my Citroen. I have lost the screw.

The Part number of the screw is 6923C6 with the dimensions as DIAM 6X100-16.

I was planning to buy something from a local hardware store if someone can help me interpret the dimensions.

Thanks in advance.