Splits on separator while ignoring separators nested inside a ${...} interpolation, so ${VAR:-/default/path}:/target:ro splits into 3 parts.
separator
${...}
${VAR:-/default/path}:/target:ro
Splits on
separatorwhile ignoring separators nested inside a${...}interpolation, so${VAR:-/default/path}:/target:rosplits into 3 parts.