Pulse period derivatives as function of pulse period for GC pulsars with a strong magnetic field and/or short characteristic age. Numbers according to Table 2. Grey points indicate single pulsars in the Galactic disc, the grey solid line the death-line, the black solid lines are the spin-up line according to Eq. (5) and a line shifted by a factor 7 in Ṗ. Dashed lines of constant magnetic field (black) and constant age (blue) are marked with their respective values.