5.6.1.4 Maximum and Mininum Values in Table Columns

  HEASARC uses the following keywords to specify the limits on data in a table column. They are analogous to the DATAMAX and DATAMIN keywords used for arrays.

• TDMAXn is the maximum value in column n of a table, exclusive of null or fill values.
• TDMINn is the minimum value in column n of a table, exclusive of null or fill values.
• TLMAXn is the maximum permissible value in column n of a table.
• TLMINn is the minimum permissible value in column n of a table.

For example, if the third column in a table of positions was declination, then the following keywords might be present.

TTYPE3  = 'DEC     '
TFORM3  = '1E      '
TUNIT3  = 'DEGREES '
TLMAX3  =                90.00
TLMIN3  =               -90.00
TDMAX3  =                46.00
TDMIN3  =               -63.10

HEASARC also recommends the following restrictions when these keywords are used:

• The data type of the keyword value should be the same as that of the data in the column it describes.
• The keywords are to refer to all elements of a vector column
• As with DATAMAX and DATAMIN, the keywords apply to the values after any scaling prescribed by the values of the TZEROn and TSCALn keywords has been applied.
• Values of TDMINn less than those of TLMINn and values of TDMAXn greater than those of TLMAXn are permissible; the meaning is not defined in this convention.
• If the value of the keyword for the maximum is less than that of the value of that for the minimum, then the values are taken to be undefined.