symbols after game titles on roms - NES emulation

[Dann-Oh]

I'm new to emulation and roms so pardon this question if it is basic and silly so here it goes. What are the different symbols after the game roms in the title line. Do they have a significance? see the below for an example of what I'm talking about. After I extract the files from their compressed folder I would have expected to see a game rom, Contra, instead I see multiple rom files. If I a looking for the original (unadulterated) rom I would think I would want the "Contra (U) [!]" file. What do the symbols mean, any help would be awesome? [U], [b1], [!], [hFFE], [o3]

I will be putting this on a Raspberry Pi, running RetroPie 3.6 (i believe, I will be upgrading to RetroPie 4.1 shortly).

Files available after extraction:
Contra (U) [!]
Contra (Beta) [t1]
Contra (Beta) [t1][o1]
Contra (J) [b1]
Contra (J) [b2]
Contra (J) [b3]
Contra (J) [hFFE]
Contra (J) [hFFE][b1]
Contra (J) [hFFE][b2]
Contra (J) [hM04] (PAL)
Contra (J) [hM04]
Contra (J) [o1]
Contra (J) [o1][T+Eng1.0_MadHacker]
Contra (J) [o2]
Contra (J) [p1][T+Eng1.0_MadHacker]
Contra (J) [p1][T+Eng1.0_MadHacker][o1]
Contra (J) [p2][T+Eng1.0_MadHacker].nes
Contra (J) [p2][T+Eng1.0_MadHacker][o1]
Contra (J) [T+Chi]
Contra (J) [T+Chi][a1]
Contra (J) [T+Chi_MS emumax]
Contra (J) [T+Eng1.0_MadHacker]
Contra (J) [T+Pol1.0_Dr00id88]
Contra (J) [T+Pol1.0_Dr00id88][o1]
Contra (J) [T+Por1.0_Trans-Center]
Contra (J) [T+Por1.12_GTP]
Contra (J) [T+Rus_Chronix]
Contra (J) [t1]
Contra (J) [t2]
Contra (J) [t3]
Contra (J) [t4]
Contra (J) [t5]
Contra (J) [t6]
Contra (J) [t7]
Contra (J) [T-Chi]
Contra (KC)
Contra (PC10) [b1]
Contra (PC10)
Contra (U) [!]
Contra (U) [o1]
Contra (U) [o2]
Contra (U) [o3]
Contra (U) [o4]
Contra (U) [o5]
Contra (U) [T+Ger1.0_StarTrans]
Contra (U) [T+Por90%_Groxo]
Contra (U) [T+Por90%_ZeroNet]
Contra (U) [T+Por100%_TRB]
Contra (U) [T+Spa_DJ_Traducciones]
Contra (U) [T+Spa100%]
Contra (U) [t1]
Contra (U) [t2]
Contra (U) [t3]
Contra (With +4 Menu) (Unl) [o1]
Contra (With +4 Menu) (Unl) [t1]
Contra (With +4 Menu) (Unl) [a1]
Contra (With +4 Menu) (Unl)
Contra 1993 (Unl).nes

[gabrielmop]

I'm new to emulation and roms so pardon this question if it is basic and silly so here it goes. What are the different symbols after the game roms in the title line. Do they have a significance? see the below for an example of what I'm talking about. After I extract the files from their compressed folder I would have expected to see a game rom, Contra, instead I see multiple rom files. If I a looking for the original (unadulterated) rom I would think I would want the "Contra (U) [!]" file. What do the symbols mean, any help would be awesome? [U], [b1], [!], [hFFE], [o3]

I will be putting this on a Raspberry Pi, running RetroPie 3.6 (i believe, I will be upgrading to RetroPie 4.1 shortly).

Files available after extraction:
Contra (U) [!]
Contra (Beta) [t1]
Contra (Beta) [t1][o1]
Contra (J) [b1]
Contra (J) [b2]
Contra (J) [b3]
Contra (J) [hFFE]
Contra (J) [hFFE][b1]
Contra (J) [hFFE][b2]
Contra (J) [hM04] (PAL)
Contra (J) [hM04]
Contra (J) [o1]
Contra (J) [o1][T+Eng1.0_MadHacker]
Contra (J) [o2]
Contra (J) [p1][T+Eng1.0_MadHacker]
Contra (J) [p1][T+Eng1.0_MadHacker][o1]
Contra (J) [p2][T+Eng1.0_MadHacker].nes
Contra (J) [p2][T+Eng1.0_MadHacker][o1]
Contra (J) [T+Chi]
Contra (J) [T+Chi][a1]
Contra (J) [T+Chi_MS emumax]
Contra (J) [T+Eng1.0_MadHacker]
Contra (J) [T+Pol1.0_Dr00id88]
Contra (J) [T+Pol1.0_Dr00id88][o1]
Contra (J) [T+Por1.0_Trans-Center]
Contra (J) [T+Por1.12_GTP]
Contra (J) [T+Rus_Chronix]
Contra (J) [t1]
Contra (J) [t2]
Contra (J) [t3]
Contra (J) [t4]
Contra (J) [t5]
Contra (J) [t6]
Contra (J) [t7]
Contra (J) [T-Chi]
Contra (KC)
Contra (PC10) [b1]
Contra (PC10)
Contra (U) [!]
Contra (U) [o1]
Contra (U) [o2]
Contra (U) [o3]
Contra (U) [o4]
Contra (U) [o5]
Contra (U) [T+Ger1.0_StarTrans]
Contra (U) [T+Por90%_Groxo]
Contra (U) [T+Por90%_ZeroNet]
Contra (U) [T+Por100%_TRB]
Contra (U) [T+Spa_DJ_Traducciones]
Contra (U) [T+Spa100%]
Contra (U) [t1]
Contra (U) [t2]
Contra (U) [t3]
Contra (With +4 Menu) (Unl) [o1]
Contra (With +4 Menu) (Unl) [t1]
Contra (With +4 Menu) (Unl) [a1]
Contra (With +4 Menu) (Unl)
Contra 1993 (Unl).nes

U - USA Game Region
J - Japanese Game Region
E - Europe Game Region (not on your list, but you will find someday)

Contra (U) [T+Por100%_TRB] = Means that the game is 100% translated do Portuguese (or brazilian Portuguese)

Beta = Means that the game is not the final version

Don't know about the other ones, but i think is something to do about translation and region too