[daip] New Client Reply - [!MXR-193922]: asymmetry in gethead puthead

[Jan Wagner]

New Client Reply: asymmetry in gethead puthead

This behaviour, existence of read-only keywords, is not mentioned in EXPLAIN PUTHEAD.

When one tries puthead of say 'naxis4' the message "KEYWORD NOT RECOGNIZED" is also very misleading. 

31DEC12 EXPLAIN PUTHEAD tells: "If PUTHEAD does not recognize a keyword as part of its basic list, it will attempt to find it as a header keyword and create a new one if not. Therefore, be careful with KEYWORD, errors will be added to the header as new keywords."   

But 'naxis4' does not get added, despite the error. Because PUTHEAD already seems to check if a keyword exists and checks if it is read-only, the error message "KEYWORD NOT RECOGNIZED" could be replaced with "KEYWORD IS PROTECTED" or similar? This _might_ be simple to add...?

(before all I think the primary references HELP and EXPLAIN should be correct and clear; all additional more lengthy information is fine in the potentially outdated cookbook)

Ticket Details
===================
Ticket ID: MXR-193922
Department: AIPS Data Processing
Priority: Default
Status: Open
Link:  https://help.nrao.edu/staff/index.php?_m=tickets&_a=viewticket&ticketid=1353