What is in Fortran 90 but not in F

Here is a brief description of what is in Fortran 90, but not in F.

Any F program is also a Fortran 90 program.

An F program does not have:

 o  alternate returns        o  implicit typing
 o  block data               o  labels
 o  fixed source form        o  namelist i/o
 o  include                  o  statement functions
 o  internal procedures

An F program cannot have the following statements:

 o  common         o  equivalence      o  goto
 o  continue       o  entry            o  sequence
 o  data           o  format           o  do while

An F program requires that:

• all variables be declared, and that any attributes be specified in the declaration statement
• all keywords and intrinsic procedure names are in lowercase and are reserved
• each F procedure must be in a module
• all variables, types, and procedures declared in a module must have their access attribute (public or private) declared explicitly
• some declarations come in a restricted order
• all F functions must not have side effects, except they may do formatted I/O to the terminal and have a stop statement
• an open statement must indicate position, status, and action