Introduction

Some uses of CCSL require as input only the Crystal Data. More often, a file of what the crystallographer usually thinks of as his data is needed as well. This will typically be a list of items, all similar in format, e.g. indexed reflection or intensity data.

At present such files are usually read by FORTRAN fixed format READ statements. CCSL free format read routines are gradually being introduced instead, in cases where the fixed format causes problems. An example is in GRLSQ, the Least Squares Refinement of a structure for which it is required to group together several reflections on input, to compare against one calculated value. Such data are read by SUBROUTINE INOBGR, which is required to read an unknown number of integers followed by a real number (with decimal point). This is not simple using FORTRAN READ.

Another application of free format is the routine RDDATA, which reads $h,k,l$ and a set of other numbers, with the inclusion of a comment facility, so that such a list can be headed by some identifying title.