MMJ

MMJ is a SFS 5636 (Finland) cable designation: M = 1st letter: plastic insulation ('muovieristetty'; fi.wikipedia 'M = Muovi'); PVC per the Reka sheet; M = 2nd letter: plastic sheath ('muovivaippa'); UV-protected PVC per the Reka sheet; J = Plastic-sheathed cable or cord ('Tarkoittaa muovivaippakaapelia/johtoa. MMJ'); MMJ = MMJ: plastic-insulated, plastic-sheathed installation cable, copper, PVC, 300/500 V; a trailing S means one core is green-yellow earth, N means none. 300/500 V, 70 C conductor, 160 C short circuit (5 s). SFS 2091, SS 424 02 19-3, NEK 535 (Reka datasheet).

1 coding system recognises this code

SFS 5636 (Finland)

Symbol	Meaning
`M`	1st letter: plastic insulation ('muovieristetty'; fi.wikipedia 'M = Muovi'); PVC per the Reka sheet
`M`	2nd letter: plastic sheath ('muovivaippa'); UV-protected PVC per the Reka sheet
`J`	Plastic-sheathed cable or cord ('Tarkoittaa muovivaippakaapelia/johtoa. MMJ')
`MMJ`	MMJ: plastic-insulated, plastic-sheathed installation cable, copper, PVC, 300/500 V; a trailing S means one core is green-yellow earth, N means none. 300/500 V, 70 C conductor, 160 C short circuit (5 s). SFS 2091, SS 424 02 19-3, NEK 535 (Reka datasheet)

Fire behaviour (EU CPR)

PVC sheath (M, MMJ).
Typically targeted, as declared by makers for this kind of construction in the examples this site checked (not the class of this cable):
- Eca N1XV-R, Ahlsell (seller)
- Cca-s3,d1,a3 FG16OR16, Nexans (La Triveneta Cavi)
- Eca U1000 R2V, Nexans (La Triveneta Cavi)
- Eca N2XSY, Waskönig+Walter (10 kV datasheet)
Listed as sources, alphabetically by maker. No maker pays to appear here.

A CPR class is declared by the maker in its Declaration of Performance and printed on the sheath (EN 50575 cl 7). This decoder does not assign one. What the CPR classes mean →

Sources: EN 13501-6 draft and FprEN 50575:2014 final draft (drafts, not the published texts); IEC 60332-3-24:2000+A1:2008; EN 13501-3 draft A2.