- type: setup command
- function: define obstructions in the global coordinate system (Z,X)
- sequence: must follow floor_coodinates and preceed track
- Command syntax, including use of equations and subcommands, is discussed in 7.2.

&obstruction_data

STRING input = NULL;

long periods = 1;

long disable = 0;

double y_spacing = 0;

double y_limit[2] = {-10, 10};

&end

STRING input = NULL;

long periods = 1;

long disable = 0;

double y_spacing = 0;

double y_limit[2] = {-10, 10};

&end

- input — Name of SDDS file containing obstruction data. The file must contain two columns, Z and
X, giving the global coordinates of points on the obstruction contour in the Y = 0 plane, in units of
meters. The file may contain more than one page, with each page giving a closed contour for a
separate obstruction. At present, obstructions are considered to extend over Y : [-∞,∞]. The file
must also contain three parameters:
- Superperiodicty —- integer parameter giving the number of repetitions of the defined obstructions in the full ring. For example, for the 40-sector APS ring, if the obstruction data covered a single sector, then the value would be 40.
- XCenter, ZCenter — floating point parameters giving the position of center of the ring in meters. The obstructions are rotated about this center if periodic.

- periods — Obstructions represented by the provided data are to be repeated in a periodic fashion the number of times given. It is assumed that the system is a storage ring.
- disable — If nonzero, then the command is ignored.
- y_spacing — If nonzero, then the input file is expected to have data for multiple vertical planes,
instead of the default y = 0 midplane. The plane for each page is identified by the parameter Y in
the input file. The data must be sorted in increasing order of Y, which can be accomplished using
sddssort, e.g.,
sddssort input.sdds -parameter=Y
- y_limit — Allows specifying maximum limits on the vertical coordinate, beyond which particles are lost.

optimize