  AIMS: We examine whether ejection phenomena from accreting T Tauri stars can
be described by only one type of self-collimated jet model. METHODS: We present
analytical kinematic predictions valid soon after the Alfv\'en surface for all
types of steady magnetically self-confined jets. RESULTS: We show that extended
disc winds, X-winds, and stellar winds occupy distinct regions in the poloidal
speed vs. specific angular momentum plane. Comparisons with current
observations of T Tauri jets yield quantitative constraints on the range of
launching radii, magnetic lever arms, and specific energy input in disc and
stellar winds. Implications on the origin of jet asymmetries and disc magnetic
fields are outlined. CONCLUSIONS: We argue that ejection phenomena from
accreting T Tauri stars most likely include three dynamical components: (1) an
outer self-collimated steady disc wind carrying most of the mass-flux in the
optical jet (when present), confining (2) a pressure-driven coronal stellar
wind and (3) a hot inner flow made of blobs sporadically ejected from the
magnetopause. If the stellar magnetic moment is parallel to the disc magnetic
field, then the highly variable inner flow resembles a "Reconnection X-wind",
that has been proven to efficiently brake down an accreting and contracting
young star. If the magnetic moment is anti-parallel, then larger versions of
the solar coronal mass ejections are likely to occur. The relative importance
of these three components in the observed outflows and the range of radii
involved in the disc wind are expected to vary with time, from the stage of
embedded source to the optically revealed T Tauri star phase.

Astrophysics