This "L0_YMD" directory contains an alternative directory tree structure where the date directories are converted into separate year, month, and day directories. For example, "20110417" becomes "2011/04/17".
It's important to note that this alternative directory tree structure is NOT compatible with the SECCHI SolarSoft routines. Those routines expect the directory tree structure in the "L0" directory, where year, month, and day are combined into a single string (e.g. "20110417").
As with the regular tree, this alternative directory tree contain SECCHI Level 0.5 FITS files for the Ahead (a) and Behind (b) spacecraft, organized into the following categories:
Note that COR1 and COR2 data are split between the "img" and "seq" trees. COR2 observations typically toggle between single total-brightness images and three-image polarization sequences, with the details depending on the available telemetry rate. COR1 typically takes only polarization sequences, but can also have interspersed "img" and "seq" images when the telemetry rate is low.