GENERAL	LabCode	Laboratory code as assigned by the lab that conducted the analysis.
	Add LabCode	Any additional lab codes that were assigned to the date.
	DatingTechnique	Either 'beta-counting' (i.e. radiometry) or 'AMS'. As the first AMS measurements were performed in 1977 (see figure 1) all samples analysed before 1977 will automatically be categorised under 'Beta-counting'.
	YearOfDating	"Year when the sample was dated by the laboratory. In case a period is given, the earliest year is recorded."
	CopyrightLicense	Licence under which the data was published (if applicable).
	ConsultedLab 1	Either yes or no to indicate whether the lab was consulted for additional details on the sample.
	Reference	Original publication(s) that mentioned the date.
	ReliabATOrigPub	Any comments about whether the date was reliable according to its original publication.
	Notes	"Any other comments (e.g. whether a lithological or lithogenetic cross-section is available, short description of the definition for basal peat as used by the original publication that mentioned the date)."
AGE	F14CMean	Reported mean age in conventional 14C years (BP).
	F14CSD	Reported standard deviation of the mean age in 14C years.
	ReservoirCorrected14CMean	"If applicable and reported, the mean age in 14C years (BP) after applying a reservoir correction."
	CalMean	Reported mean calibrated age in years before common era (BCE) / common era (CE).
	CalSD	Reported standard deviation of the mean age in calendar years.
	UnknownMean	"Reported mean age, unknown whether the data represent uncalibrated or calibrated ages."
	UnknownSD	"Reported standard deviation of the mean age, unknown whether the data represent uncalibrated or calibrated ages."
	Delta13	13? value used to correct the dating result for isotopic fractionation.
	Delta13source	Either 'measured' or 'estimated' to indicate whether the reported 13? value was quantified in the laboratory or that a standard estimate was applied.
	CarbonContent	Measured carbon content (%C) of the dated sample material.
LOCATION	LocationDescription	Description of the location where the sample was taken.
	X 2	"Column listing all X-coordinates in the Dutch RD-new projection, either reported or transformed from reported longitude."
	Y 2	"Column listing all Y-coordinates in the Dutch RD-new projection, either reported or transformed from reported latitude."
	XYuncertainty	Reported uncertainty of measured X and Y coordinates.
	Lat	"Column listing latitude, in case location is only reported as geographical coordinates. "
	Lon	"Column listing longitude, in case location is only reported as geographical coordinates."
	LLuncertainty	"Reported uncertainty of measured latitude and longitude, in case location is only reported as geographical coordinates. "
	XYcategory 3	"Type of coordinate data; either 'recorded', 'field' or 'placename'."
ELEVATION	RASTERVALUE	"Elevation of the location of the date, taken from the Dutch national digital elevation model (AHN2)."
	DepthBelowSurface	"Reported depth of the sample (in case only one number is given) below the surface at the time of sampling, given in cm."
	DepthBelowSurfaceFrom	"Reported depth of the upper boundary of the sample below the surface at the time of sampling, given in cm."
	DepthBelowSurfaceTo	"Reported depth of the lower boundary of the sample below the surface at the time of sampling, given in cm."
	AverageFromToBelowSurface	"Average of the reported upper and lower boundary of the sample below the surface at the time of sampling, given in cm."
	DepthBelowSurfaceTotal	Column with concatenated results of columns 'DepthBelowSurface' and 'AverageFromToBelowSurface'.
	DepthNAPboBelowSurfaceTotal	"Conversion of 'DepthBelowSurfaceTotal' to values in m NAP (Dutch Ordnance Datum, approximately mean sea level), using the column 'RASTERVALUE'."
	DepthNAP	"Reported depth of the sample (in case only one number is given) in m NAP (Dutch Ordnance Datum, approximately mean sea level)."
	DepthFromNAP	"Reported depth of the upper boundary of the sample in m NAP (Dutch Ordnance Datum, approximately mean sea level)."
	DepthToNAP	"Reported depth of the lower boundary of the sample in m NAP (Dutch Ordnance Datum, approximately mean sea level)."
	AverageFromToNAP	"Average of the reported upper and lower boundary of the sample below the surface at the time of sampling, given in m NAP (Dutch Ordnance Datum, approximately mean sea level)."
	DepthNAPtotal	Column with concatenated results of columns 'DepthNAP' and 'AverageFromToNAP'.
	DepthNAPfromALLSOURCES	"Column with concatenated results of columns 'DepthNAPBelowSurfaceTotal' and 'DepthNAPtotal', providing an elevation value for each date that was accompanied by elevation information (not corrected for potential compaction effects)."
LANDFORM AND STRATIGRAPHY	Landform	"Either 'Valley', 'Pingo', 'Depression', 'Peatland (unspecified)', 'Ridge', 'Mound', 'Channel fill', 'Bog (hollow)', or 'Bog (hummock)'."
	LandformGrouping	Grouped landform classes following table 6 of the manuscript.
	Stratigraphy	"Either 'Upperlimit', 'Lowerlimit', or 'Within' to indicate whether the sample was taken at the top of the peat layer, the base of the peat layer, or somewhere within the peat layer, respectively."
SAMPLE INFORMATION	SampleThickness 4	Sample thickness in cm.
	SampleDetails	"Any information on the sample material, species, etc."
	SampleContext	"Either 'Environmental', 'Artefact' or 'Anthropogenic' (the latter in case of sediment sampled from anthropogenically disturbed contexts)."
	SampleMaterial	Peat' / 'Organic' / 'Gyttja' / 'Wood' / 'Charred' / 'Carbonate' / 'Gliede' (Dutch term used for amorphous organics in peatlands) / 'Dopplerite'.
	MeasuredFraction	Details on measured fraction as provided by the referenced paper for the date.
	SampleType	Either 'bulk' or 'macro' to distinguish between bulk samples and samples consisting of plant macrofossils.
	SpeciesType 5	"In case of a 'bulk' SampleType this automatically becomes 'undefined'. In case of a 'macro' SampleType, this column lists either 'terrestrial', 'aquatic', 'both', or 'NR'. Terrestrial and aquatic distinguish between plant species that might be affected by a reservoir effect."
	Aboveground	"In case of a 'bulk' SampleType this automatically becomes 'undefined'. In case of a 'macro' SampleType either 'yes', 'no' or 'NR' must be selected to distinguish between seeds/leaves/stems or roots respectively."
	Pretreatment	"Either 'ABA' or 'onlyA' to indicate whether the ABA protocol was used or only the first A, respectively."
CALIBRATION	OxCal	OxCal command used to calibrate the date.
	from_	"Calibrated age, lower limit of confidence interval in cal y BP."
	to_	"Calibrated age, upper limit of confidence interval in cal y BP."
	F_	Confidence interval (%).
	mu	"Calibrated age, average in cal y BP."
	sigma	Standard deviation (in calendar years) of average calibrated age.
	Chronostratigraphy	Chronostratigraphical period assigned to the calibrated date.
QUALITY ASSESSMENT	QA_*****	Scores obtained for the twelve quality criteria (***** refers to the twelve headers all starting with QA).
	Qd	Total score for dating quality.
	QT	Total score for taphonomic quality.
	Q	Total quality score.
	Quadrant	Resulting confidence quadrant (expressed in the four colours of table 3).
		
	"1. In case lab data differed from data provided by publications, the lab was followed. For one entry in the case study this led to a major change in the age (GrN-5460, the datelist in which this date is mentioned contains an error)."	
		
	"2. In case no coordinates were provided by the original publications but the field of sampling was indicated, coordinates were retrieved based on georeferenced historical maps where the old field boundaries were indicated. If only a nearby village was mentioned, its central coordinates were registered."	
		
	"3. These categories may after the quality assessment be replaced by a case-study-dependent value, to be used as uncertainty range in further analyses (e.g. 'field' might be replaced by an uncertainty value of 100 m)."	
		
	"4. In case no sample thickness was retrieved, a default sample thickness can be defined after the quality assessment to use in further analyses."	
		
	"5. To determine whether terrestrial or aquatic plants were used for dating the species was looked up in the Dutch online encyclopaedia of species (Soortenbank.nl, 2020). Samples that consisted of Sphagnum mosses that lacked further information on terrestrial or aquatic growth habit were listed as 'Undefined'."	
