The List is the fourth edition in a series which started in 1971.¹²³ It is based on ed. 21 of the Flora van Nederland. 6 The criteria for inclusion of a taxon in the List (§ 2) are: all taxa are well recognizable, and: all ‘wild’ taxa are included. For practical reasons the year 1825 is chosen as the starting point for 'indigenous' taxa. Special criteria are defined for species appearing after 1825. The meaning of the Standard List number (§ 3) is explained with some examples. All taxa included have a code for their frequency (UFK; see § 4 – first number: estimated frequency in 1940, second number: estimated frequency in 1990), two codes for the ‘ecological group’ (§ 5), and (facultative) a code for the Red Data List category (§ 6). The total number of Standard List taxa amounts to 1448.