ISAM 7 statements (get next key and return it) now support dynamic variables. They do not, however, support auto-extension of arrays. So if you want to use an auto-extend array variable, you must first initialize each element; for example,

DIMX IKEY(1),S,0,AUTO_EXTEND

...

! load ISAM keys into an auto-extending array of dynamic elements

DO WHILE ERF(CH)=0

    I = I + 1

    IKEY(I) = ""    ! must initialize element to get auto-extension!

    ISAM #CH, 7, IKEY(I)

LOOP