This compound glyph of a boat, acal(li), represents the name of the town, Acalhuacan. The canoe or boat, which is painted a terracotta color (typically used in this codex for wood) is marked by two vertical, parallel lines. The -can locative suffix is not shown visually.
According to Danièle Dehouve, these lines represent rain drops as expressed in face paint [xahual(li)], and they provide the phonetic element for "hua." Dehouve also points to the possibility of tlaolxahualli, facial paint from rubber, to provide the "hua." [See, Dehouve, "The Rules of Construction of an Aztec Deity," Ancient Mesoamerica, 31 (2020), 7–28. See, in particular, page 15. She also mentions Lacadena's proposal of the verb huahuana, "to make lines in the earth, make lines on paper."] Presumably, liquid rubber could be painted on the face to create these thick black lines about the width a finger would make.
Alfonso Lacadena has called this the Tenochtitlan-Tlatelolco "double-stroke sign." [See his article, "The wa1 and was2 Phonetic Signs and the Logogram for WA in Nahuatl Writing," The PARI Journal 8:4 (2008), 38.] Leonardo Manrique felt the "hua" sign could be translated as "owner, possessor," but as Lacadena points out, it does not work in all cases. Sometimes it is a logogram and sometimes is is a phonogram in a complement role. Differing from Dehouve, Lacadena suggests that the double-stroke sign comes from the verb huahuana, whose definition includes to make or mark lines, citing Karttunen 1992. It is interesting that the double-stroke sign is a reduplication that is both alphabetic and hieroglyphic. Lacadena also writes about a hua "leaves sign" associated with Tetzcoco that involves two leaves (a phonogram) and a grasping hand (for possessor) hua sign, which he sees as conveying "meaning and sound."
Supporting that this "hua" element is an addition meant to help spell out the place name Acalhuacan, the iconographic symbol of a canoe (glossed "canoa") from folio 4 verso of the Codex Mendoza does not have the two vertical lines. Berdan and Anawalt, in translating the name of this place glyph, recognize the "hua" element by referring to the town as having canoes.
c. 1541, or by 1553 at the latest
boats, launches, canoes, wood, barcos, lanchas, canoas, madera, double-strike sign, double-stroke sign
acal(li), boat or canoe, https://aztecglyphs.wired-humanities.org/content/acalli
huaxahual(li), face paint, https://nahuatl.wired-humanities.org/content/xahualli
tlaolxahual(li) liquid rubber face paint, https://nahuatl.wired-humanities.org/content/tlaolxahualli
"Place of Those Who Have Canoes" (Berdan & Anawalt, v. 1, p. 167)
El Lugar Donde Tienen Canoas
Codex Mendoza, folio 17 verso, https://digital.bodleian.ox.ac.uk/objects/2fea788e-2aa2-4f08-b6d9-648c00..., image 45 of 188.
The Bodleian Libraries, University of Oxford, hold the original manuscript, the MS. Arch. Selden. A. 1. This image is published here under the UK Creative Commons, “Attribution-NonCommercial-ShareAlike 3.0 License” (CC-BY-NC-SA 3.0).