Meaning of $^2[\,1/2]$ terms in atomic spectroscopy

I was trying to analyze some atomic emission spectroscopy data and I encountered unfamiliar notation of the terms for me.


Commonly, the electronic states of the atoms can be described by quantum numbers using the term notation ("L-S coupling"). The terms are given as: $^{2S+1}L\_{J}$, where $S$ is the total spin quantum number, $J$ is the total angular momentum quantum number and $L$ is the total orbital quantum number in spectroscopic notation.


However, in this table there are also terms having notations without letters ($S$,$P$,...), like $^{2}[\,1/2]^\mathrm{o}$ (black box). What does that mean and why are there separate cases for $J = 0$ and $J = 1$?


[**Edit**] The data has been taken from NIST Atomic Spectral Database for Ne I (neutral neon in spectroscopic notation).
[NIST database](https://physics.nist.gov/cgi-bin/ASD/lines1.pl?spectra=Neon%20I&limits_type=0&low_w=&upp_w=&unit=1&submit=Retrieve%20Data&de=0&format=0&line_out=0&en_unit=0&output=0&bibrefs=1&page_size=15&show_obs_wl=1&show_calc_wl=1&unc_out=1&order_out=0&max_low_enrg=&show_av=2&max_upp_enrg=&tsb_value=0&min_str=&A_out=0&intens_out=on&max_str=&allowed_out=1&forbid_out=1&min_accur=&min_intens=&conf_out=on&term_out=on&enrg_out=on&J_out=on)
The notation, asked in this posted has already been explained here [Notation key by NIST](https://www.nist.gov/pml/atomic-spectroscopy-compendium-basic-ideas-notation-data-and-formulas/atomic-spectroscopy-2)


[![enter image description here](https://i.stack.imgur.com/O8dMb.png)](https://i.stack.imgur.com/O8dMb.png)


