private static Value concat(final ValueList values) {
        if (values.size() == 0) {
            return Value.of("");
        }

        if (values.size() == 1) {
            return values.get(0);
        }

        int overflowCount = 0;
        final StringBuilder sb = new StringBuilder();
        boolean firstNonoverflowFound = false;
        for (Value v : values) {
            if (OVERFLOW_VALUE == v) {
                overflowCount++;
            } else {

                final String strValue = v.getAsString();
                if (overflowCount > 0 && firstNonoverflowFound && !(".".equals(strValue))) {
                    for (int i = 0; i < overflowCount - strValue.length() + 1; i++) {
                        sb.append("0");
                    }
                }
                overflowCount = 0;
                firstNonoverflowFound = true;
                sb.append(strValue);
            }
        }
        return Value.of(sb.toString());
    }
concats values Formula-internally. Takes care of the spillover character _
main/src/main/java/cgeo/geocaching/utils/formulas/Formula.java