The following set of criteria was used while collecting experimentally verified plant gene promoters:

1. 1.   There was published experimental evidence of TSS position(s) of a gene. For genes with multiple TSS, a start position nearest to a CDS was used, unless there was evidence of predominance of another position (positions of additional TSSs were given in identifier lines of sequences).
2. 2.   Length of promoter sequence upstream of chosen TSS was at least 200 bp; all stored promoter sequences are of the same length (251 bp), where the position 201 corresponds to the TSS, i.e. collected sequences occupy the region [-200 : +51], with the TSS in the position +1, and thus, present proximal promoters mentioned above.
3. 3.   An entry corresponds to a gene mapped to a genomic sequence.
4. 4.   Various alleles of the same gene are represented in the database by a single entry.
5. 5.   Genes with more than one non-allelic copy in a genome, as well as paralogous genes, are represented as different entries.