  Accretion disks around stellar-mass black holes offer unique opportunities to
study the fundamental physics of standard thin disks, super-Eddington disks,
and structure that may be connected to flux variability. These local analogues
of active galactic nuclei (AGN) are particularly attractive for their
proximity, high flux, and peak emissivity in the X-ray band. X-ray calorimeter
spectrometers, with energy resolutions of 2-5 eV, are ideally suited to study
accretion in stellar-mass black holes. The results will make strong tests of
seminal disk theory that applies in a broad range of circumstances, help to
drive new numerical simulations, and will inform our understanding of AGN
fueling, evolution, and feedback.
