On the internet I found this code. It searches the mesh for the minimum point on the Y. Why Y? How to find the minimum point on the X or Z?
Const rhObjectMesh = 32
Dim strObject, arrVertices
strObject = Rhino.GetObject("Select mesh", rhObjectMesh)
arrVertices = Rhino.MeshVertices(strObject)
Dim v, pointMin
If IsArray(arrVertices) Then
For Each v In arrVertices
If Not isArray(pointMin) Then
pointMin = v
ElseIf v(1) < pointMin(1) Then
pointMin = v
End If
Next
Call Rhino.AddtextDot("YMin", pointMin)
End If
Regards, Pavel