What is a varible produced through binary dimension reduction called?

If I take k binary variables and reduce them to one k-long string variable consisting of zeros and ones. What would you call the new variable?

For example, for unit i, xi1 = 1, xi2 = 0, xi3 = 0, and xi4 = 1. So for that unit i above, the new variable's value would be 1001.

Is there a name for this type of variable? Maybe a "composite variable," or a "descriptive index", or a "binary-style index."

You have created a bit map (bit vector, bit array) from the individual yes/no data points.

Internally in a computer program you can represent that as an integer in base $2$ and store it that way.