求问CHKTRE(ICODE)这个函数

ycjwanok

这边要用到 但看不明白 问问各位  CHKTRE(ICODE)函数是什么作用的？ 返回值个表示什么意思？
手册里给的解释如下
CALL CHKTRE(ICODE)
, W- Y( n! ]* qIf the case contains Type 4 (or greater) buses with in-service branches then an error condition is
* y: L* k: l; A& rreturned. Counts number of islands not containing a Type 3 (swing) bus. It may be inappropriate to
call this subroutine with generators converted; since there will be no Type 3 buses, it will simply
0 |1 N" g! o( e! g( t% c$ b; ?count every island (finding at least one unless there is no working case).
ICODE Error code (integer output):
5 k$ {8 Y+ F, @3 S. B! v: y0 No errors.
$ Z* s: P2 k4 H2 u-1 No in-service buses remaining.
-2 There are Type 4 buses with in-service branches connected.
; y. ^& ?! W% L8 T8 B- i0 u) T; t>0 Number of islands without a Type 3 bus.
太谢谢了