Mishnayos Niddah Perek 8 Mishnah 1

A woman who sees a blood stain on her flesh adjacent to her vagina [beit haturpa], i.e., a place where blood that originated in her vagina could be found, becomes ritually impure, as there is a concern that it originated in the uterus and is menstrual blood. And if it was discovered on her flesh in an area not adjacent to her vagina she remains ritually pure, as it certainly did not originate in the uterus. If the stain was discovered on her heel or on the tip of her large toe, although it is not adjacent to her vagina she is ritually impure, as blood from the uterus could have reached there. In a case where the stain was discovered on her leg or on her feet, if it was on the inner side she is ritually impure, as blood from the uterus could have reached there. If it was on the outer side she is ritually pure, and if it was on the sides, either from here, i.e., on the front of her leg or foot, or from there, i.e., on the back of her leg or foot, she is also ritually pure, as blood from the uterus could not have reached there. In a case where the woman saw a blood stain on her robe, if it was from the belt and below she is ritually impure, as blood from the uterus could have reached there; if it was from the belt and above she is ritually pure. In a case where she saw the stain on the end of the sleeve of the robe, if the sleeve can reach adjacent to her vagina she is ritually impure; and if not, i.e., if the stain is in a place on the sleeve that does not reach adjacent to the vagina, she is ritually pure. If it was a robe which she would remove and with which she would cover herself at night, wherever on the robe that the stain is found, the stain renders her ritually impure, due to the fact that the robe moves while the woman is asleep and therefore the blood could have originated in the uterus. And likewise with regard to a kerchief [bapoleyos], no matter where the blood is found on the kerchief, the woman is impure.

הָרוֹאָה כֶתֶם עַל בְּשָׂרָהּ כְּנֶגֶד בֵּית הַתֻּרְפָּה טְמֵאָה. וְשֶׁלֹּא כְנֶגֶד בֵּית הַתֻּרְפָּה, טְהוֹרָה. עַל עֲקֵבָהּ וְעַל רֹאשׁ גּוּדָלָהּ, טְמֵאָה. עַל שׁוֹקָהּ וְעַל פַּרְסוֹתֶיהָ, מִבִּפְנִים, טְמֵאָה. מִבַּחוּץ, טְהוֹרָה. וְעַל הַצְּדָדִין מִכָּאן וּמִכָּאן, טְהוֹרָה. רָאֲתָה עַל חֲלוּקָהּ, מִן הַחֲגוֹר וּלְמַטָּה, טְמֵאָה. מִן הַחֲגוֹר וּלְמַעְלָה, טְהוֹרָה. רָאֲתָה עַל בֵּית יָד שֶׁל חָלוּק, אִם מַגִּיעַ כְּנֶגֶד בֵּית הַתֻּרְפָּה, טְמֵאָה. וְאִם לָאו, טְהוֹרָה. הָיְתָה פוֹשַׁטְתּוֹ וּמִתְכַּסָּה בוֹ בַּלַּיְלָה, כָּל מָקוֹם שֶׁנִּמְצָא בוֹ כֶתֶם, טְמֵאָה, מִפְּנֵי שֶׁהוּא חוֹזֵר. וְכֵן בַּפַּלְיוֹם: