That would be shown as X(+), with X being the 'variable', at the level without any pluses or minuses, and the (+) showing that you fluctuate between no plus and one plus. Thus you get an average of a half plus
-----BEGIN GEEK CODE BLOCK-----
Version: 3.12
GCS/M/S d- s-: a--- C++ UL P+ L+ E W++>+++$ N o? K? w !O M-- V? PS++ PE Y+ PGP- t+@ 5++(+++) X+@ R>+ tv+ b++(+++) DI++ D+ G e->+++++(*) h! !r-- y?
------END GEEK CODE BLOCK------
-----BEGIN SE4 CODE BLOCK-----
Version: 1.0
L GdY $?* Fr! C-- S* T Sf Tcp-(+) A++ M++(+++++) Mp!P R!- Pw Fq-->++ Nd Rp+ G%
------END SE4 CODE BLOCK------