Logging events when running a CTMC

I haven’t tried this, but I think you could add a 6th entry to your state vector (u0=[990, 10, 0, 0, 0,0]) and set it to a different value for each transition function.

for example

function ctmc_jumps_S_to_L_by_I(u)
    u[1] -= 1  # S decreases
    u[2] += 1  # L increases
    u[6] = 1
end

function ctmc_jumps_S_to_L_by_A(u)
    u[1] -= 1  # S decreases
    u[2] += 1  # L increases
    u[6] = 2
end

Not as nice as something built-in, but worth a try.