Agni Purana (Jyotisha Selections) · by Vyasa
Chapter 3 · Name Letters and Chakras
युद्धजयार्णवः (चक्राणि)
सेवाचक्रं प्रवक्ष्यामि लाभालाभार्थसूचकम् ।पिता माता तथा भ्राता दंपती च विशेषतः ॥ १ ॥
In the full Agni Purana this is chapter 132, verse 1.
I will tell the Seva chakra, which shows gain and loss. Father, mother, brother and especially husband and wife.
Simple meaning: A wheel is told for reading gain and loss between father, mother, brother, and husband and wife.
तस्मिंश्चक्रे तु विज्ञेयं यो यस्माल्लभते फलम् ।
In this wheel you can tell who gains from whom. Draw six lines upright and eight lines across.
कोष्ठकाः पञ्चत्रिंशच्च तेषु वर्णान्समालिखेत् ।
The wheel has thirty-five squares. Five vowels and then the consonants are written in them.
ककारादिहकारान्तान्हीनाङ्गांस्त्रीन्विवर्जयेत् ।
Three imperfect letters are left out. The five classes are named Siddha, Sadhya, Susiddha, Ari and Mrityu.