An Improvement Location Certificate or ILC is an inspection of a parcel by a licensed surveyor to determine possible encroachments or other matters that could be adverse from a land surveying standpoint.
 ​ ILC's are often if not always required on a closing of a property or at the completion of any construction (improvements) on a property, normally residential in nature. 
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An ILC IS NOT 
a. It is not a survey. 
b. It does not locate exact boundaries. 
c. It does not establish property corners. 
d. It is not to be legally relied upon for locations of property lines or future improvements. 

Sometimes the ILC will reveal a possible encroachment or some other evidence of a boundary dispute. In this case, a true survey, (i.e. improvement survey plat or boundary  survey plat) would be required to clarify or resolve any discrepancies