INTENTs is used to provide a series of text strings that give guidance to various stages of data handling. They can be directives to telescopes to, for example, do active phasing at the VLA or hold the previous phase. They could be used by the correlator. Or they can be used to tell pipeline processing that a scan is to be used for one or more specific types of calibration. For now, the intents are written to the VEX file as comments with the scans.
The arguments of INTENTs are up to 25 strings of up to 80 characters each. Note that each string should be in quotes and they should be separated by commas. If the line ends with a comma, the next line can be used for the next string. If no INTENTs are given, they default to the previous scan. If any are given, they all return to blank unless given again again. If NONE is specified, all intents are cleared.
SCHED does not parse most INTENTs. But some, especially related to the VLA phasing, are recognized and appropriate actions are taken.
An intent may be made to target a specific antenna by starting with the station name followed by a colon. Use the same station name as used in the station catalog. If no station name is given, the INTENTs will be assumed to apply to all stations for which it is meaningful. An example line with a station might address asking the VLA to phase but not some other interferometer with: INTENT = 'VLA:AUTOPHASE_DETERMINE'.
Some established values of INTENTs in the VLA environment are listed here. Also some requested for other instruments are listed. Most will not be used in VLBI schedules. A VLBI specific list has not been generated. Of interest for the VLA are DETERMINE_AUTOPHASE and DETERMINE_OFFSET_POINTING.
This above list is from VLA documentation. For VLBI, the following are also used, although the prefered method of creating them is through the VLAMODE and VLAPEAK parameters. SCHED will not allow mixing methods of specifing these aspects of the observing.