Currently, data specified in the LOCUS line must start from position 13 in the UGENE implementation of the GenBank format. However, it is not essential according to the GenBank format specification (ftp://ftp.ncbi.nih.gov/genbank/gbrel.txt):
3.4.4 LOCUS Format
18.104.22.168 : Important notice about parsing the LOCUS line
Users who process the data elements of the LOCUS line should use a
token-based parsing approach rather than parsing its content based on
fixed column positions.
When a file is read, implement a token-based, not positional, parting of the LOCUS line. On writing a GenBank file keep the historical indentation, if possible.