• Because the length of a variable length array is, in general, not known until after it is read, the library must allocate the memory, and the user must free it with nc_free_vlen().
• VLEN data must be handled in a special struct:

  /* This is the type of arrays of vlens. */
  typedef struct {
      size_t len; /* Length of VL data (in base type units) */
      void *p;    /* Pointer to VL data */
  } nc_vlen_t;
  

• VLENs must be read and written all at once - that is, the whole array at one time.

2007 Unidata NetCDF Workshop for Developers and Data Providers > Using NetCDF-4 Features, Part 2