How to select levels

kshell_ui.py asks you to choose what angular momentum and parity you want the resulting levels to have:

J, parity, number of lowest levels
(ex. 100          for 100 +parity, 100 -parity levels w/o J-proj. (default)
    -5           for lowest five -parity levels,
    0+3, 2+1     for lowest three 0+ levels and one 2+ levels,
    1.5-1, 3.5+3 for lowest one 3/2- levels and three 7/2+ levels)
    range        for a range of levels) :

• Entering an integer $N$ will ask KSHELL to produce the $N$ lowest lying energy levels, regardless of angular momentum and parity. Example: Inputting 1337 will produce the 1337 lowest lying energy levels.
• Prepending a plus sign ($+$) or a minus sign ($-$) to the integer will specify which parity you want to calculate the levels for. Note that your chosen nuclide and model space might only be able to produce either positive or negative parity levels. Example: +1337 will produce the 1337 lowest lying positive parity levels.
• You can request the $N$ lowest lying levels of a specific angular momentum and parity. Example: 0+3 will produce the three lowest lying levels with angular momentum 0 and positive parity.
• You can request several different specific angular momentum and parity levels. Example: 1.5-1, 3.5+3 will produce the lowest lying level of angular momentum 3/2 and negative parity, as well as the three lowest lying levels of angular momentum 7/2 and positive parity.
• The range functionality lets you easily select $N$ levels for a range of different angular momenta. Any invalid choice will be filtered away, like choosing integer angular momenta for a nucleus of half integer angular momenta, or choosing a parity which the interaction does not support. In the following example we select 10 positive parity levels for angular momenta 0, 1, 2, and 3:

range
Start spin: 0
End spin (included): 3
Number of states per spin: 10
Parity (+, -, both): +
Chosen states: ['0+10', '1+10', '2+10', '3+10']