"PER_FROM"|"DESCRIPTION"|"NOTES"
"AA"|"PALAEOLITHIC"|"From North Yorkshire County Council Archaeological Record System System"
"AB"|"UPPER PALAEOLITHIC"|"From North Yorkshire County Council Archaeological Record System System"
"AC"|"LOWER PALAEOLITHIC"|"From North Yorkshire County Council Archaeological Record System System"
"AD"|"EARLY POSTGLACIAL"|"From North Yorkshire County Council Archaeological Record System System"
"BA"|"MESOLITHIC"|"From North Yorkshire County Council Archaeological Record System System"
"BB"|"EARLY MESOLITHIC"|"From North Yorkshire County Council Archaeological Record System System"
"BC"|"LATE MESOLITHIC"|"From North Yorkshire County Council Archaeological Record System System"
"BD"|"LATE MESOLITHIC/EARLY NEOLITHIC"|"From North Yorkshire County Council Archaeological Record System System"
"CA"|"NEOLITHIC"|"From North Yorkshire County Council Archaeological Record System System"
"CB"|"EARLY NEOLITHIC"|"From North Yorkshire County Council Archaeological Record System System"
"CC"|"MIDDLE NEOLITHIC"|"From North Yorkshire County Council Archaeological Record System System"
"CD"|"LATE NEOLITHIC"|"From North Yorkshire County Council Archaeological Record System System"
"CE"|"LATE NEOLITHIC/EARLY BRONZE AGE"|"From North Yorkshire County Council Archaeological Record System System"
"DA"|"BRONZE AGE"|"From North Yorkshire County Council Archaeological Record System System"
"DB"|"EARLY BRONZE AGE"|"From North Yorkshire County Council Archaeological Record System System"
"DC"|"MIDDLE BRONZE AGE"|"From North Yorkshire County Council Archaeological Record System System"
"DD"|"LATE BRONZE AGE"|"From North Yorkshire County Council Archaeological Record System System"
"DE"|"LATE BRONZE AGE/EARLY IRON AGE"|"From North Yorkshire County Council Archaeological Record System System"
"EA"|"IRON AGE"|"From North Yorkshire County Council Archaeological Record System System"
"EB"|"EARLY IRON AGE"|"From North Yorkshire County Council Archaeological Record System System"
"EC"|"MIDDLE IRON AGE"|"From North Yorkshire County Council Archaeological Record System System"
"ED"|"LATE IRON AGE"|"From North Yorkshire County Council Archaeological Record System System"
"EE"|"LATE IRON AGE/EARLY ROMAN"|"From North Yorkshire County Council Archaeological Record System System"
"FA"|"PREHISTORIC MULTI PERIOD"|"From North Yorkshire County Council Archaeological Record System System"
"GA"|"PREHISTORIC UNKNOWN PERIOD"|"From North Yorkshire County Council Archaeological Record System System"
"HA"|"ROMAN"|"From North Yorkshire County Council Archaeological Record System System"
"HB"|"1st  CENTURY"|"From North Yorkshire County Council Archaeological Record System System"
"HC"|"2nd  CENTURY"|"From North Yorkshire County Council Archaeological Record System System"
"HD"|"3rd  CENTURY"|"From North Yorkshire County Council Archaeological Record System System"
"HE"|"4th  CENTURY"|"From North Yorkshire County Council Archaeological Record System System"
"HF"|"5th  CENTURY"|"From North Yorkshire County Council Archaeological Record System System"
"JA"|"SAXON"|"From North Yorkshire County Council Archaeological Record System System"
"JB"|"5th  CENTURY"|"From North Yorkshire County Council Archaeological Record System System"
"JC"|"6th  CENTURY"|"From North Yorkshire County Council Archaeological Record System System"
"JD"|"7th  CENTURY"|"From North Yorkshire County Council Archaeological Record System System"
"JE"|"8th  CENTURY"|"From North Yorkshire County Council Archaeological Record System System"
"JF"|"9th  CENTURY"|"From North Yorkshire County Council Archaeological Record System System"
"JG"|"10th CENTURY"|"From North Yorkshire County Council Archaeological Record System System"
"JH"|"11th CENTURY"|"From North Yorkshire County Council Archaeological Record System System"
"KA"|"MEDIEVAL"|"From North Yorkshire County Council Archaeological Record System System"
"KB"|"11th CENTURY"|"From North Yorkshire County Council Archaeological Record System System"
"KC"|"12th CENTURY"|"From North Yorkshire County Council Archaeological Record System System"
"KD"|"13th CENTURY"|"From North Yorkshire County Council Archaeological Record System System"
"KE"|"14th CENTURY"|"From North Yorkshire County Council Archaeological Record System System"
"KF"|"15th CENTURY"|"From North Yorkshire County Council Archaeological Record System System"
"LA"|"POST MEDIEVAL"|"From North Yorkshire County Council Archaeological Record System System"
"LB"|"16th CENTURY"|"From North Yorkshire County Council Archaeological Record System System"
"LC"|"17th CENTURY"|"From North Yorkshire County Council Archaeological Record System System"
"LD"|"18th CENTURY"|"From North Yorkshire County Council Archaeological Record System System"
"MA"|"MODERN"|"From North Yorkshire County Council Archaeological Record System System"
"MB"|"19th CENTURY"|"From North Yorkshire County Council Archaeological Record System System"
"MC"|"20th CENTURY"|"From North Yorkshire County Council Archaeological Record System System"
"NA"|"HISTORIC MULTI PERIOD"|"From North Yorkshire County Council Archaeological Record System System"
"NR"|"NO RECORD/NOT RECORDED"|"From North Yorkshire County Council Archaeological Record System System"
"OA"|"HISTORIC UNKNOWN PERIOD"|"From North Yorkshire County Council Archaeological Record System System"
"PA"|"UNKNOWN PERIOD"|"From North Yorkshire County Council Archaeological Record System System"