请高手详解下这段汇编宏代码

L MACRO sText:REQ            
    LOCAL str, chr, flag, cchr      
        cchr TEXTEQU <>              
        str  TEXTEQU <>              
        flag TEXTEQU <.>            
        FORC chr, <&sText>            
            IFIDN flag, <\>     
                IFIDN <&chr>, <\>           
                    cchr TEXTEQU <"\">      
                ENDIF
                IFIDN <&chr>, <|>           
                    cchr TEXTEQU <"!!">   
                ENDIF
                IFIDN <&chr>, <n>            
                    cchr TEXTEQU <13,10>
                ENDIF
                IFIDN <&chr>, <0>           
                    cchr TEXTEQU <0>
                ENDIF
                flag TEXTEQU <.>
            ELSE               
                IFIDN <&chr>, <\>           
                    flag TEXTEQU <\>
                    cchr TEXTEQU <>
                ELSE                        
                    cchr CATSTR <">, <chr>, <">
                ENDIF
            ENDIF
            IFDIF str, <>                  
                IFDIF flag, <\>
                    str CATSTR str, <,>
                ENDIF
            ENDIF
            IFDIF cchr, <>                  
                str CATSTR str, &cchr
            ENDIF
        ENDM
        EXITM str
    ENDM
我的水平很菜，请尽可能详细一些 ，尤其是其中的比如FORC这个循环展开后是什么样子，<&sText>中&符号的作用？