“水位线”的英语？

小船迎风航行,船体沿着水位线严重倾斜.The boat was pointing and leaning sharply along the water line.已发送项目文件夹的水位线文本框不能是空的.The Sent Items folder watermark box cannot be empty.“已发送邮件”文件夹高水位线不能等于零.The Sent Items folder high watermark cannot e...