Here we describe and discuss the various data entities (structures)
that MIDAS recognizes.
They are stored in an internal binary format,
accessible only through MIDAS and fall into the following categories:
The individual data points in an image are referred to as ``pixels''
and in a table they are called ``elements'' . The paragraphs
below describe the structure of descriptors, and keywords, and
the methods for specifying the individual data values in images
and tables.
Note is no special syntax for file names in MIDAS. You can use any legal name of your host file system for images, tables and fit files. However, a name beginning with a digit or using any of the characters
+, -, *, /, `, !, |, ( and ), should be avoided, because these symbols will cause problems in e.g. the COMPUTE/IMAGE command. If you do want to use a file name with these special characters in a COMPUTE/IMAGE command you have to enclose the full name in quotes, i.e.
Midas 456> COMPUTE/IMAGE res = 12 + "quasar01+12.bdf"The length of these names is, in principle, limited to 60 characters for MIDAS applications (which is the size of keywords IN_A, OUT_A, used in most procedures to store the image, table names...).
Also file names like abc.bdf.mine will not be appreciated by all MIDAS applications.
As mentioned before, file names are case sensitive in MIDAS on Unix systems; names for descriptors and keywords are not. Thus, referring to a keyword with name KEYA may be done e.g. via keyA or Keya.