Language Structure

TSL is a line oriented language where the PI submits a target list as an ASCII file (or several appended files.) Each submission file is fundamentally structured as a series of blocks which contain parameter/value pairs. The blocks are hierarchical and represent the nested elements of the language as described below.

STANDARD BLOCKS

COMMON
A collection of parameter/value pairs which apply to any subsequent GROUP, TRACK, or ACTION unless explicitly overridden in a subsequent block.

TRACK
One or more actions that take place during a single HET trajectory for a specified DEC and RA or for a non-sidereal object.

GROUP
A set of associated TRACKs or ACTIONs with specific operational characteristics. For example, a GROUP can specify:

A set of TRACKs which must be executed on the same night
(Group type = AND)
A set of TRACKs of which only a subset are required
(Group type = POOL)
A set of ACTIONs to be executed in a specific sequence on the same night even if they are in different tracks
(Group type = SEQ)
A set of TRACKs to be executed in a specific order on one or more nights
(Group type = ORD)
There may be any number of groups within a single program but groups do NOT cross program boundaries.
Group names must be unique only within a given program.
Grouping of targets is a powerful control, but adds to execution timing constraints. Consider carefully whether a conceptual grouping really requires this executional grouping.

ACTION
A single schedulable event. Examples include a science exposure or a calibration lamp.

LIST BLOCKS
There are two additional block types, TARGET_LIST and ACTION_LIST, representing aggregate TRACKs (with implied ACTIONs) and ACTIONs, respectively. These allow the PI to specify TARGET and ACTION parameters in a row/column format where the first row is the list of parameters names and each subsequent row in the block is a list of TARGET and/or ACTION values.