Ockham's razor

be portable

to at least VMS and Unix
• isolate system dependent features in a small number of routines (the VOS)
• choose to support only the minimum number of features really needed ("reduced instruction VOS")

  be easy to install

• do not require system privileges (any user can install it)
• do not require excessive or unusual machine resources
• do not require excessive disk space (any user can install it)
• have a non-intricated directory organization

  be under complete control of developers

• using an ad-hoc XAS file format
• do not depend on commercial libraries, use only home-grown or public domain code
• not developed under overarching external-designed environment
• written almost entirely in Fortran

  be efficient

• small library routines
• layered design of library routines
• ad-hoc XAS file format uses native representation
• make use of memory allocation
• client-server graphics approach
• X11 and PostScript graphics

  be easy to program with

• written almost entirely in Fortran
• layered design of library routines
• isolate specific competences in single modules

  be easy to use

• consistent and versatile user interface (command-line, interactive and parameter file support)
• no ad-hoc monitor or shell
• access to operating system environment variables
• simple procedures replaced by front-end dispatcher programs

  be mission independent

• using an ad-hoc XAS file format
• using environment variables and file keyword to control mission- and instrument-specific items.

  be open

• file format designed to be easily mappable to FITS (for easy export/exchange to/with major packages)
• XAS files immediately usable from IDL or SAOimage
• isolate interface problems in conversion modules
  sax.iasf-milano.inaf.it/Sax/Xas/occam.html :: original creation 2002 Sep 04 16:20:26 CEST :: last edit 2002 Sep 04 16:20:26 CEST