The data is always stored in one array, of the type matching the data type (i.e. for 'int' it's an 'int[]'). The data should be stored in the array in standard scan-line order. That is the samples go from the top-left corner of the code-block to the lower-right corner by line and then column.

The member variable 'offset' gives the index in the array of the first data element (i.e. the top-left coefficient (ulx,uly)). The member variable 'scanw' gives the width of the scan that is used to store the data, that can be different from the width of the block. Element '(x,y)' of the code-block (i.e. '(ulx,uly)' is the top-left coefficient), will appear at position 'offset+(y-uly)*scanw+(x-ulx)' in the array of data.

A block of data can have the progressive attribute set. Data is progressive when it is obtained by successive refinement and the values in this block are approximations of the "final" values. When the final values are returned the progressive attribute must be turned off.

The classes DataBlkInt and DataBlkFloat provide implementations for int and float types respectively.