Selective serotonin reuptake inhibitor. Selective serotonin reuptake inhibitors (SSRIs), also known as serotonin-specific reuptake inhibitors or serotonergic antidepressants,[1] are a class of drugs that are typically used as antidepressants in the treatment of major depressive disorder and anxiety disorders.
Then you're looking for the midpoint! The midpoint of a line segment is the point located midway between the endpoints of the line segment. This tutorial tells you about the midpoint of a line segment.
The mean center is  a point constructed from the average x and y values for the input feature centroids. Use projected data with this tool to accurately measure distances. The x and y values for the mean center point features are attributes in the Output Feature Class. The values are stored in the fields XCOORD and YCOORD. The Case Field is used to group features for separate mean center computations.