The file steering.snap contains corrector magnet power supply settings, such as might be saved to an SDDS file using the sddssnapshot program.
The input files are SDDS files. There must be a string column named ControlName, Device, or DeviceName that contains the process variable names. There must also be a string column named ValueString, a numerical column named Value, or a column of either type with the name specified by the -dataColumn option; this column contains the final value for the corresponding process variable.
When data is supplied in a string column, sddscaramp needs a way to determine if the data value is actually a number rather than a literal string value (e.g., an enumerated value). The optional IsNumerical column can be used for this purpose. If supplied, this column should contain character values y or n, indicating that each PV (respectively) does or does not have numerical values. If the IsNumerical column does not exist or is not of character type, then sddscaramp uses an internal algorithm to decide whether the data for each PV is numerical or not. This may fail in the case of enumerated values that contain numbers, resulting in incorrectly restored values. For reliable results, the use of IsNumerical with string data is required. If the data is in a numerical column to begin with, of course, there is no ambiguity.