  The observables in a single-channel $2$-body scattering problem remain
invariant once the amplitude is multiplied by an overall energy- and
angle-dependent phase. This invariance is known as the continuum ambiguity.
Also, mostly in truncated partial wave analyses (TPWAs), discrete ambiguities
originating from complex conjugation of roots are known to occur. In this note,
it is shown that the general continuum ambiguity mixes partial waves and that
for scalar particles, discrete ambiguities are just a subset of continuum
ambiguities with a specific phase. A numerical method is outlined briefly,
which can determine the relevant connecting phases.
