The main aim of our project was to prepare material for further archaeological and chronological studies, so it was obvious, that we should put stress on the calibration of radiocarbon dates. The problem of calibration appears complex and controversial. Particularly we have spent a lot of time to find the best method of presentation of calibration results in a simple, numerical form (Krzanowski et al. 1994). Finally we have decided to show the calibration results in the form of intervals of calendric age which contain the real value of calendric age with probability 68.3% and 95.4% (these values correspond with 1SD and 2SD intervals for Gaussian distribution). Fig. 1 shows the method of determination these intervals. The same method is used by many well known calibration programs  e.g. calibration program by M. Stuiver and P. Reimer  CALIB 3.0 (Stuiver & Reimer 1993) or the Groningen calibration program (van der Plicht 1993).
Radiocarbon dates included in the ANDY database were calibrated using the Gliwice Calibration Program (Pazdur & Michczynska 1989) ver. 5.2. The calibration curves used for the calculation were taken from "Radiocarbon", Vol. 35 (1993) and they are practically the same as the curves used by the CALIB 3.0. The only difference is that we decided to finish the calibration curve at 9439 BC (the end of German oak and pine calibration by B. Kromer and B. Becker) and don't include the results obtained by mass spectrometry on corals, which extend the range of calibration to over 30000 years BP (Bard et al. 1993). Because measurement points building the calibration curve before 10.000 BP are located considerably rarer than earlier than this date we decided that it would be the best point to finish the calibration curve, which would be used for the treatment of radiocarbon dates from archaeological sites. Moreover, all dates were calibrated without correction for systematic age difference between the northern and southern hemisphere, estimated by Vogel et al. (1993) to be about 40 yr. We suppose that this correction, obtained for wood samples from South Africa (latitude between 25dS and 35dS), would not be valid for region near the equator.
Calibration programs written in few countries were compared in 1989 (Aitchison et al. 1989) and reasonably good agreement was found between them. All these programs use the same statistical method of calculation, and differ only in the form of result presentation. We will not discuss this problem here, presenting only an example table with the results of calibration the same radiocarbon dates by Gliwice Calibration Program and CALIB 3.0 (Tables 1 and 2). Unimportant differences between these results (23 years) are caused by technical aspects of programming. Moreover Fig. 1 and Fig. 2 present probability distributions of calendric age obtained by Gliwice (Fig. 1) and CALIB 3.0 (Fig. 2) programs, which differ only in the presentation form.
Gd5695  320±40 conv BP  
68.3%  cal AD  1621  1644  15.60% 
cal AD  1515  1593  52.21%  
95.4%  cal AD  1482  1654  95.56% 
Gd4662  780±80 conv BP  
68.3%  cal AD  1173  1297  68.29% 
95.4%  cal AD  1343  1391  7.04% 
cal AD  1152  1318  76.11%  
cal AD  1112  1147  4.57%  
cal AD  1044  1105  7.88%  
Gd5682  1210±50 conv BP  
68.3%  cal AD  773  890  67.37% 
cal AD  729  731  0.94%  
95.4%  cal AD  908  959  10.14% 
cal AD  692  897  85.38%  
Gd3534  1870±45 conv BP  
68.3%  cal AD  117  219  66.52% 
cal AD  90  92  1.62%  
95.4%  cal AD  63  250  95.33% 
Gd6213  2400±80 conv BP  
68.3%  cal BC  547  389  48.25% 
cal BC  758  679  19.47%  
95.4%  cal BC  283  255  1.67% 
cal BC  786  360  93.95%  
Gd8011  3720±60 conv BP  
68.3%  cal BC  1996  1986  3.41% 
cal BC  2147  2026  51.30%  
cal BC  2193  2155  13.59%  
95.4%  cal BC  2282  1940  95.47% 
Gd3442  4405±30 conv BP  
68.3%  cal BC  2995  2926  49.45% 
cal BC  3039  3017  15.41%  
cal BC  3073  3068  3.48%  
95.4%  cal BC  3047  2921  79.50% 
cal BC  3091  3054  16.01%  
Gd4394  5400±150 conv BP  
68.3%  cal BC  4357  4041  67.87% 
95.4%  cal BC  3859  3818  1.23% 
cal BC  4540  3938  94.16%  
GaK2470  7830±180 conv BP  
68.3%  cal BC  6783  6463  50.81% 
cal BC  6895  6841  7.25%  
cal BC  6996  6921  10.18%  
95.4%  cal BC  6286  6241  1.26% 
cal BC  6328  6295  0.90%  
cal BC  7097  6344  91.07% 
Gd5695  
Radiocarbon Age BP  320±40  
% area enclosed  cal AD age ran  relative area under probability distribution 

68.3 (1s) cal AD  1514  1593  .76 
1620  1645  .24  
95.4 (2s) cal AD  1481  1654  1.00 
Gd4662  
Radiocarbon Age BP  780±80  
68.3 (1s) cal AD  1170  1300  1.00 
95.4 (2s) cal AD  1040  1100  .08 
1110  1320  .84  
1340  1390  .08  
Gd5682  
Radiocarbon Age BP  1210±50  
68.3 (1s) cal AD  727  732  .03 
772  891  .97  
95.4 (2s) cal AD  690  898  .89 
908  960  .11  
Gd3534  
Radiocarbon Age BP  1870±45  
68.3 (1s) cal AD  89  94  .05 
116  220  .95  
95.4 (2s) cal AD  62  251  .99 
Gd6213  
Radiocarbon Age BP  2400±80  
68.3 (1s) cal BC  760  680  .29 
550  390  .71  
95.4 (2s) cal BC  790  360  .99 
280  260  .01  
Gd8011  
Radiocarbon Age BP  3720±60  
68.3 (1s) cal BC  2190  2030  .91 
2000  1980  .09  
95.4 (2s) cal BC  2290  1940  1.00 
Gd3442  
Radiocarbon Age BP  4405±30  
68.3 (1s) cal BC  3075  3067  .07 
3040  3016  .23  
2997  2926  .70  
95.4 (2s) cal BC  3094  3051  .19 
3049  2920  .81  
Gd4394  
Radiocarbon Age BP  5400±150  
68.3 (1s) cal BC  4360  4040  1.00 
95.4 (2s) cal BC  4540  3940  .99 
3860  3820  .01  
GaK2470  
Radiocarbon Age BP  7830±180  
68.3 (1s) cal BC  7000  6920  .16 
6900  6840  .12  
6780  6460  .73  
95.4 (2s) cal BC  7100  6340  .95 
6330  6240  .03 
Final remarks
We do not discuss the basic problems of database system here. The raeder may find a comprehensive introduction to the theory of databases at the manual "An introduction to database systems" written by C.J. Date (Date, 1977). On the other hand particular problems of radiocarbon databanks were discussed by Renee Kra (Kra, 1988).
We are aware of the fact, that the solutions we prefer, may be not satisfactory for all. Consequently we expect many observations, even critical reproof, about our database.
References
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Bard E., Arnold M., Fairbanks R.G., and Hamelin B., 1993. 230Th234U and 14C Ages Obtained by Mass Spectrometry on Corals. radiocarbon, Vol. 35, No. 1, 191201.
Date C.J., 1977. An introduction to database systems. AddisonWesley Publishing Company, Inc., Reading, Massachusetts, USA.
Kra R.S., 1988. Updating the past. The establishment of the International Radiocarbon Data Base. American Antiquity, Vol. 53, No. 1, 118125.
Krzanowski A., Michczynski A., Pazdur M.F., Ziólkowski M.S., 1994. Komputerowa baza danych datowan radioweglowych rejonu Andów Srodkowych. Zeszyty Naukowe Politechniki Slaskiej, Geochronometria 10, pp. 139151.
Pazdur M.F., Michczynska D.J., 1989. Improvments of the Procedure for Probabilistic Calibration of radiocarbon dates. radiocarbon, Vol. 31, 824832.
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van der Plicht J., 1993. The Groningen Radiocarbon Calibration Program. Radiocarbon, Vol. 35, No. 1, 231239.
Vogel J.C., Fuls A.M., Visser E., and Becker B., 1993. Pretoria Calibration Curve for ShortLived Samples, 19303350 BC. radiocarbon, Vol. 35, No. 1, 7387.