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
! N3 y4 ?7 G# }" U" H1 \/ _5 nCALL CHKTRE(ICODE)
1 Z' q# C4 t' z  DIf the case contains Type 4 (or greater) buses with in-service branches then an error condition is
returned. Counts number of islands not containing a Type 3 (swing) bus. It may be inappropriate to
6 ^  S5 v3 K7 L- i' Gcall this subroutine with generators converted; since there will be no Type 3 buses, it will simply
7 z- f9 s6 _9 ^: C  |* f; K3 kcount every island (finding at least one unless there is no working case).
9 {3 v8 z& n! B# k' DICODE Error code (integer output):
0 No errors.
+ O& W# v& g8 W) V, c/ j-1 No in-service buses remaining.
. t' U6 c3 ?% Y4 K-2 There are Type 4 buses with in-service branches connected.
>0 Number of islands without a Type 3 bus.
2 Y2 v6 v% i6 L- M' Z太谢谢了