The date [day,week,month,year] x1=d1=k1 is recurrence/repetition of the date [day,week,month,year] of the first event x2=d2, for the x3=k3'rd time, in system x3.
x1 is x2 (li; no default value assumed, but - unless explicitly overridden - assumed to be expressed with significant figures) years old according to standard of measurement x3; colloquial form: x1 is/has x2 (years (of age)).