After saving data values in a Survo data file by FILE MEDIT (or by FILE SHOW etc.), the correctness of values may be checked by retyping values in FILE MEDIT by using a CHECK specification. During checking only values of variables given in the CHECK specification are readily displayed and they are protected. Thus typically at least the name or the id number of the observation is given. Also values of derived fields are shown. Other fields seem to be blank but they become visible when the retyping procedure proceeds. If a new value typed in a blank field is different from the original one, an error message is displayed and the user may decide which is the correct value. Example: CHECK=Commune,Province FILE MEDIT FINLAND M = More information on FILE MEDIT