$ cat xmlg.awk
BEGIN { RS="<";         FS=">"; ORS="\r\n";

        # Change this to alter how many close-tags in a row are needed
        # before a row of data is printed.
        DEP=1
        SEP="\t"
        }

# Skip weird XML specification lines or blank records
/^\?/ || /^$/   {       next    }

# Handle close tags
/^[/]/  {
        N=D;    while((N>0) && ("/"STACK[N] != $1))     N--;

        if("/"STACK[N] == $1)   D=(N-1);
        POP++;

        if(POP == DEP)
        {
                if(!HEADER++)
                {
                        split(ARG[1], Z, SUBSEP);
                        printf("%s %s", Z[2], Z[3]);
                        for(N=2; N<=ARG_; N++)
                        {
                                split(ARG[N], Z, SUBSEP);
                                printf("%s%s %s", SEP, Z[2], Z[3]);
                        }

                        printf("\n");
                }

                printf("%s", DATA[ARG[1]]);
                for(N=2; N<=ARG_; N++)
                        printf("%s%s", SEP, DATA[ARG[N]]);
                printf("\n");
        }
        next
}

# Handle open tags
{
        gsub(/^[ \r\n\t]*/, "", $2);    # Whitespace isn't data
        gsub(/[ \r\n\t]*$/, "", $2);
        sub(/\/$/, "", $(NF-1));

        # Reset parameters
        POP=0;

        M=split($1, A, " ");
        STACK[++D]=A[1];

        if((!MAX) || (D>MAX)) MAX=D;    # Save max depth

        # Handle parameters
        Q=split(A[2], B, " ");
        for(N=1; N<=Q; N++)
        {
                split(B[N], C, "=");
                gsub(/['"]/,"", C[2]);

                I=D SUBSEP STACK[D] SUBSEP C[1];
                if(!SEEN[I]++)
                        ARG[++ARG_]=I;

                DATA[I]=C[2];
        }

        if($2)
        {
                I=D SUBSEP STACK[D] SUBSEP "CDATA";
                if(!SEEN[I]++)
                        ARG[++ARG_]=I;

                DATA[I]=$2;
        }
}

$ sed 's/env="\([^"]*\)" env="\([^"]*\)"/env="\1\2"/g' 3.xml | awk -f xmlg.awk
rel ver mod name        node env        ins ip  ins ip
123     on      ac1     10.192.0.1      10.192.0.2
123     on      ac2     10.192.0.3      10.192.0.4
123     on      pr      10.192.0.5      10.192.0.6
123     off     ac1     10.192.0.7      10.192.0.6
123     off     ac2     10.192.0.8      10.192.0.6
123     off     pr      10.192.0.9      10.192.0.6

$