The e-mail interface of the CATS is designed like CGI for the call of the basic procedures: select and match from the html-forms and the program is a lexical analyser, distinguishing keywords and parameters from the electronic letter sent to the address `email@example.com'. To obtain instruction about operations via the mail-server the user can send a letter to this address with a single string: 'help'.
The majority of parameters, distinguishing by the analyser for the requested procedures are reported via environment variables, and long lists via temporal files. The output of result is forseen in the same formats as in other forms of the access to the CATS. They are usual the table format, the FITS TABLE format, PostsScript for figures, both in compressed or non-compressed forms. A binary format of output data (when compression) is transformed to ASCII by one of the standard UNIX convertors by user request: uuencode, mime or ship; and sent to the user's address with the operations report. There is a possibility to sent a maximum size of a letter to be replied. When errors occur, the report consits of protocol of analyser operations and instructions with rules of the CATS e-mail accsess use. To escape cycling of letters, when illegal return addresses are set, or impossibility of reply delivering, the processing of requests from users with names uucp, root, daemon, etc. is not produced. The main problem appearing in the functional expanse of this kind of the interface is the support of automatical including of new catalogs and data, which are sent by users. Probably we will add new commands and descriptions, providing these possibilities, to the standard set. Here is an example of some e-mail forms, which may be sent to the CATS address for lexical analysis to the end of this year:
<arg1 arg2... >
<arg1 arg2... >
<arg1 arg2... >
object_name_1 12h35m54.2s 13d47m15 1950
object_name_2 12 35 54 13 47 15 1950
object_name_n 12:35:54 13:47:15 2000
The analysis of commands starts from the keyword ` cats' at the beginning of a line and till the command ` cats end'. Each line starts from a command or a simbol '%', defining a comment. Each line can contain several commands with their arguments. Exception to the rule is the command of beginning of a table of sources parameters. This command must be the last or single in a line. The separators of all arguments (excluding sources table) are space[s], tabulation, comma, <cr>.
Similarly, the table of sources is completed by a line starting with every valid command. Therefore, it is forbidden to use a consequence of symbols, forming a standard command, as a name prefix of a source inside of a table.
The default search window is a circle. If the parameter ' box' is set after comma, the seach will be in an error box. The units of circle radius or box side can be arcsec (default), or arcmin, or ', or ".
The formats of window radius can be following:
window box 15sec 3' - box of 12s x 3'
window box 3' - box of 3' x 3'
window circle 3' - circle with radius of 3'
window ellipse x=15sec,y=3' - ellipse 12s x 3'
All letters can be written in the upper or lower registers.
All detailed instructions can be requested by the address 'firstname.lastname@example.org' near at the middle of this year.