>>GetFldState(-1), first byte:
>>3 Field in an appended record has not been modified or deletion status has not changed for the appended record.
>>

>>IF LEFT(GetFldState(-1),1) == [3] AND ;
>>   NOT [4] $ SUBSTR(GetFldState(-1),2)
>>  ** Nothing changed in this record
>>ENDIF
>>

>
>In my case there is 4 in the iActive_Flag field, though I didn't touch the record at all. This is the default value.

Skip it. Check other field.
Or:

IF LEFT(GetFldState(-1),1) == [3] AND ;
   NOT [4] $ SUBSTR(GetFldState(-1),2)
   ** Nothing changed in this record
ELSE
   LOCAL lcFldStatStr, lcDefault, lnbFieldNo, lbSomethigIsChanged
   lcFldStatStr = SUBSTR(GetFldState(-1),2)
   lnbFieldNo   = 1
   DO WHILE NOT EMPTY(lcFldStatStr)
      IF LEFT(lcFldStatStr,1) == [4]
         IF DBGETPROP(FIELD(lnbFieldNo),[DefaultValue]) # TRANSFORM(EVAL(FIELD(lnbFieldNo)))
            lbSomethigIsChanged = .t.
            EXIT
         ENDIF
      ENDIF
      lcFldStatStr = SUBSTR(llcFldStatStr,2)
   ENDDO
   IF lbSomethigIsChanged
      ** Somethig is changed for this field
   ENDIF
ENDIF

Something like that, but not tested.